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Healthcare Provider Q&A

This Q&A document includes general information about COVID-19 vaccines and questions and answers specific to the vaccines currently in use in BC.
COVID-19 vaccine information is evolving, and as such, this Q&A will be updated as new information becomes available.

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COVID-19 disease

 
Information on COVID-19 epidemiology is continually evolving. For the most up-to-date data on COVID-19 cases, go to:
 

 
The COVID-19 pandemic has caused significant morbidity and mortality, as well as social and economic disruption in Canada and worldwide. Since their introductions, COVID-19 vaccines have shown to be very effective at preventing severe disease, including hospitalization and death due to COVID-19. COVID-19 vaccination protects not only the person being vaccinated, but also people around them, including those who are unable to get the vaccine. The more people in a community who are immunized and protected from COVID-19, the harder it is for COVID-19 to spread.
 
 
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Vaccine development and safety 

 
Factors that allowed COVID-19 vaccines to progress quickly include advances in vaccine development technology, government funding and purchase commitments, international collaboration among health professionals, researchers, industry and governments to develop the vaccines, rapid recruitment of participants for clinical trials, and streamlined vaccine approval processes by the regulatory body at Health Canada. Canada’s rigorous vaccine approval process has remained in place to assess COVID-19 vaccines. 

As for all vaccines and treatments that are authorized in Canada, Health Canada reviews the evidence and scientific data and decides whether to authorize the COVID-19 vaccine and will only do so when the evidence shows that the vaccine:
  • is safe, effective and of good quality and
  • demonstrates that the benefits outweigh the known and potential risks
Health Canada’s approval of the Pfizer-BioNTech vaccine on December 9, 2020 is an example of this accelerated process. Health Canada ensured that the Pfizer-BioNTech vaccine, laboratory studies and three phases of double-blind randomized clinical trials have shown safety, immunogenicity (ability to generate an immune response) and efficacy (ability to prevent COVID-19 disease) of this vaccine in animals and in adolescents and adults 16 years of age and older. Approximately 44,000 individuals randomized (1:1) to receive either the vaccine or placebo participated in phases 2 and 3 of the clinical trials.1  This population has been considered sufficient to approve vaccine based on safety and efficacy.

Health Canada also has processes in place to share information with other countries’ regulatory bodies including the US Food and Drug Administration and the European Medicines Agency. 

Once a vaccine is approved, vaccine safety and effectiveness are continuously monitored to detect rare serious or unexpected side effects.
 

 
The Biologic and Radiopharmaceutical Drugs Directorate (BRDD), which is part of Health Canada, supervises all aspects of vaccine production and quality control throughout the vaccine’s lifecycle. When a manufacturer develops enough scientific and clinical evidence of a vaccine’s safety, efficacy, and quality, they file a complete package of information that is submitted to BRDD for market authorization. A submission contains data from scientific studies, including laboratory and clinical studies, and information about the manufacturing process, including the manufacturing facility and manufacturing method. BRDD thoroughly reviews the submission to determine whether the benefits of a vaccine outweigh any potential risks. BRDD also reviews procedures for the manufacturer’s safety monitoring and any plans to minimize any identified risks. In addition, BRDD may visit the manufacturing site to evaluate the manufacturing process’ quality and make sure the manufacturer can carry out the necessary quality controls for the vaccine. 

The expedited review performed for COVID-19 vaccines has been possible because of a number of administrative changes to the process. These have included allowance of submission of data when available rather than the sponsor needing to wait until the entire data package is complete prior to submission. As well, for approval of these vaccines in Canada and many countries, there has been allowance for a shorter period of follow-up of people enrolled into the phase 3 clinical trials, whereas for non-pandemic vaccines, that follow-up period is typically upwards of one year. As a result, the clinical trials will continue to accrue cases and safety information for up to two years following immunization. Results from these studies will be reported in the future and will provide additional information about issues such as duration of protection from the vaccine(s).


 
 
For an effective conversation about COVID-19 vaccines, we can start from a place of compassion and understanding. Patients consistently rank healthcare providers as their most trusted source for vaccine information. Be transparent about the latest vaccine(s) information, reassure that we have a robust vaccine safety system in Canada, and emphasize vaccines’ role to protect recipients and the people around them. Your willingness to listen to the patients’ concerns will play a significant role in building trust in you and your recommendation. If a patient has concerns or questions, this doesn’t necessarily mean they won’t accept a COVID-19 vaccine. Sometimes patients simply want your answers to their questions. Once you’ve answered their questions, let them know that you are open to continuing the conversation. Encourage your patients to schedule another appointment or go to the BCCDC or ImmunizeBC websites for more information about COVID-19 vaccination. Continue the conversation about COVID-19 vaccination during future visits.

 

‎Canada has a system of local, provincial, and national surveillance to carefully monitor adverse events following immunization and detect any vaccine safety concerns. Once a vaccine is approved, its safety is continuously being monitored as long as it is used. In most provinces and territories, including BC, health care providers are legally obliged to report all serious and unexpected adverse events following immunization to the medical health officer. Every serious or concerning event is reported to the BC Centre for Disease Control (BCCDC). These reports are reviewed at BCCDC and also sent to the Public Health Agency of Canada system called the Canadian Adverse Events Following Immunization System (CAEFISS), as are reports from all provinces and territories. Additional monitoring for adverse events is being done through a system called CANVAS (Canadian National Vaccine Safety Network) through which recipients of the vaccine can enroll to self-report adverse events following receipt of the vaccine, with serious events being reported on to the regional health authority.


Vaccine safety is also monitored at the international level. The World Health Organization’s International Drug Monitoring Program collects reports from over 75 countries and uses these global data to monitor for any vaccine safety concerns. In addition, all vaccine manufacturers must report serious adverse events of which they become aware, in Canada or internationally, to Health Canada. For COVID-19 vaccines, manufacturers are expected to implement enhanced monitoring activities.

In B.C., reports on adverse events following COVID-19 immunization are available on BCCDC's COVID-19 Vaccine Safety page. 

The national reports on adverse events following COVID-19 immunization are available on Health Canada’s Reported Side Effects Following COVID-19 Vaccination in Canada page.

More information about the Canadian vaccine safety surveillance system is contained in the Canadian Immunization Guide, Part 2 – Vaccine Safety, Vaccine safety and pharmacovigilance. 
 

 

‎Vaccine providers should refer to the BC Immunization Manual, Part 5 – Adverse Events Following Immunization for criteria on reporting adverse events following immunization (AEFI), and report AEFIs to the regional health authority. Information on reporting can be found on the BCCDC’s Surveillance Forms page under Adverse Events Following Immunization. There is a short version of the AEFI form available for Health Care Providers. Those providers who work in Public Health still need to use the long form.


For more information and details on how to report an AEFI in BC go to the BCCDC Reporting Adverse Events Following Immunization: For BC Community Vaccine Providers.

 

1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. Appendix A. 2021 Jan 12 [cited 2021 Jan 13]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html



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COVID-19 vaccines in B.C.

 
The COVID-19 Vaccine Eligibility table within the BC Immunization Manual summarizes the vaccines available for use in BC and their indications.

The product specific information for the COVID-19 vaccines available in BC can be found in Part 4 - Biological Products, COVID-19 Vaccines.

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General questions

 

‎Yes, individuals should continue to practice recommended public health measures for the prevention and control of SARS-CoV-2 infection and transmission regardless of vaccination with COVID-19 vaccine. Public Health continues to monitor the epidemiology of COVID-19, as well as the duration and durability of protection from vaccination. Public Health will continue to make recommendations based on the most current evidence.

 

 

‎Vaccine efficacy is calculated using data from vaccine clinical trials. The median period of follow up of vaccine and placebo recipients from phase 3 clinical trials was 2 months. Additional information about the duration of protection will continue to accrue in the clinical trials which will gather data for at least two years. Vaccine effectiveness is calculated using real-world experience and data once a vaccine has been in use in diverse populations and settings. Vaccine effectiveness information continues to be obtained from post-marketing surveillance evaluations including studies using the test-negative design in populations being targeted for early vaccination such as health care workers, and through the long-standing Sentinel Practitioner Surveillance Network (SPSN) in Canada, which uses the test-negative study design to assess seasonal influenza vaccine effectiveness and has been running in four provinces contributing data, led by BCCDC.


Protection conferred by SARS-CoV-2 infection alone varies due to factors such as the degree of illness severity, age, and whether other comorbidities are present. Prior to the prevalence of the Omicron variant, protection due to vaccination was shown to be more durable than immunity from infection. In B.C., research demonstrated that prior to Omicron, two doses of COVID-19 vaccine provided strong protection against infection and hospitalizations and that this protection was maintained for at least four months. Vaccine effectiveness against severe outcomes due to Omicron remains high, however the longevity of protection against Omicron is still unknown and will continue to be monitored. In addition, variant-specific vaccines are in development and may be available in the coming months. 


Real world evidence suggests moderate to high vaccine effectiveness at preventing severe illness, such as hospitalization and death, which is sustained out to at least 6 months in most populations aged 12 years and older, including in older and frail populations. There is some decline in overall effectiveness noted in older adults (such as those 80 years of age and over) and residents in long term care homes over time, although protection against severe outcomes appears to be more durable than protection against infection. See information below regarding hybrid immunity.

 

 
It is estimated that half of all Canadians have contracted COVID-19 as Canada faced a 7th COVID-19 wave driven by BA.4 and BA.5 variants that are highly immune evasive.1,2 Currently, BQ.1 sub-lineages are the dominant strains in Canada which are even more immune evasive than BA.4/5.3

In the current epidemiological context of the COVID-19 pandemic, individuals who have developed immunity against COVID-19 have done so through one of the following circumstances:
  • Infection-induced immunity which describes the immune protection in an unvaccinated individual after one or more SARS-CoV-2 infections
  • Vaccine-induced immunity which is the immunity achieved by an individual who has not been infected with SARS-CoV-2 but has a primary series of any COVID-19 vaccine or has received a booster vaccination
  • Hybrid immunity is defined as the immune protection in an individual who has had one or more doses of a COVID-19 vaccine and experienced at least one SARS-CoV-2 infection before or after receiving COVID-19 vaccine4 
Evidence demonstrates that hybrid immunity may provide superior protection against COVID-19 compared to vaccination or previous infection alone.5 In a vaccinated individual, infection acts as a “dose” to increase neutralizing antibodies and may induce broader antibodies that respond better to variants. Evidence is emerging that vaccinated individuals who had been infected also demonstrate increased T cell proliferation and broadened T cell responses6 as well as increased neutralizing antibodies, compared to those without a history of infection.7 It is also noted that the level of B cell response significantly increases when individuals who have received two or three doses of COVID-19 vaccine also had a prior Omicron infection, compared to those who received two or three doses of COVID-19 vaccine but had not been infected with the Omicron strain.8 Hybrid immunity may provide better protection against reinfection with variants of concern (including Omicron).7 

Available evidence suggests protection from infection is variant dependent. For instance, infection with Omicron BA.1 most efficiently neutralizes subsequent BA.1 infections, followed by BA.2, BA.2.13 and BA.2.12.1, while the protection for subsequent infection with BA.4 and/or BA.5 sublineages would be less effective. However, those who were infected with the Omicron strain and were also vaccinated had higher neutralizing antibody responses against Omicron sublineages compared to those who had history of infection with the Omicron strain and were unvaccinated.8 It should be noted, however, that infection-induced responses vary much more widely than vaccine-induced, thus reliance on infection-induced immunity alone is risky. Vaccination is still the safest and most reliable way to induce protection against severe COVID-19.5

Immunity induced by vaccination or infection wanes against COVID-19 to varying degrees. Humoral immunity, which relies on antibodies, wanes most quickly, while cellular immunity is better preserved, regardless of how immunity was acquired. Additionally, T cells are less susceptible to immune evasion by variants, likely due to a wider range of epitopes available for T cell recognition. T cell defences, which mobilize cytotoxic capabilities and help to optimize production of antibodies from B cells, are potential explanations for protection against severe disease from COVID-19. In individuals with hybrid immunity, T cell responses were the highest.

The latest Canadian data on hybrid immunity has identified that adolescents and young adults have the highest proportion of hybrid immunity. In Canada, a greater proportion of older adults have protection from vaccination only and have not been infected as compared to younger ages, while a large proportion of children have been infected but not vaccinated.3

A recent systematic review found that the effectiveness of hybrid immunity against hospital admission or severe disease was 97.4% at 12 months with primary series and 95.3% at 6 months with first booster after the most recent infection or vaccination.9 This hybrid immunity appears to plateau after 2 doses and does not improve with more (assessed as 3 to 5) doses of vaccine.  Hybrid immunity has been observed among those infected in the pre-Omicron and Omicron era; in the period of circulation of the BA.4/5 variants, protection against hospitalization upon reinfection is >90% among individuals with hybrid immunity who have received at least two doses of vaccine.10 

 
COVID-19 vaccine would only be contraindicated if the component the individual is allergic to is also present in the influenza vaccine. Influenza vaccine and COVID-19 vaccine ingredients vary depending on the specific product. Refer to the respective product monographs for each vaccine or go to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 and influenza vaccine pages for ingredient lists. 

With the exception of FluLaval® Tetra, which contains polysorbate 80, none of the influenza vaccines contain the potential allergens that are in the mRNA vaccines (polyethylene glycol [PEG]) or viral vector based vaccines (polysorbate 80). In addition, the COVID-19 vaccines do not contain any of the potential allergens found in the influenza vaccines (e.g., ovalbumin/egg protein, thimerosal, gelatin, antibiotics). These vaccines may have some other components in common but these are not known to be allergens, i.e., sucrose and various salts. 

 

Yes. With GBS, typically the biological basis would have been an immune mediated reaction to the antigens in the vaccine. As these antigens are not shared across influenza and COVID-19 vaccines, GBS following receipt of an influenza vaccine is not a contraindication to receiving a COVID-19 vaccine.

 

 

‎1. COVID-19 Immunization Task Force. COVID-19 Seroprevalence Report: Report #22. 2022.


2. Government of Canada. COVID-19 epidemiology update. Jul 22, 2022. [Internet]. Available from: https://health-infobase.canada.ca/covid-19/archive/2022-07-22/. [Accessed 2022 Jul 7].

3. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization. Guidance on an additional COVID-19 booster dose in the spring of 2023 for individuals at high risk of severe illness due to COVID-19. 2023 Mar 3 [cited 2023 Mar 20]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-additional-covid-19-booster-dose-spring-2023-individuals-high-risk-severe-illness-due-covid-19/statement.pdf

4. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Vaccine Confidence InfoBulletin [cited 2022 September 28]. Available from: https://canvax.ca/sites/default/files/PHAC%20Vaccine%20Confidence%20InfoBulletin_Volume%202%20Issue%209%20-%20September%202022.pdf

5. World Health Organization. Interim statement on hybrid immunity and increasing population seroprevalence rates. Jun 1 2022. [Internet]. Available from: https://www.who.int/news/item/01-06-2022-interim-statement-on-hybrid-immunity-and-increasing-population-seroprevalence-rateshttps://www.who.int/news/item/01-06-2022-interim-statement-on-hybrid-immunity-and-increasing-population-seroprevalence-rates. [Accessed 2022 Jul 22].

6. Moore SC, Kronsteiner B, Longet S, Adele S, Deeks AS et al. Evolution of long-term hybrid immunity in healthcare workers after different COVID-19 vaccination regimens: a longitudinal observational study. medRxiv. 2022;1-49. Available from: https://www.medrxiv.org/content/10.1101/2022.06.06.22275865v3.full.pdf

7. Stamatatos L, Czarostki J, Wan Y-H, Homad LJ, Rubin V et al. 
mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection. Science. 2021;372(6549):1413-1418.  Available from: 

8. Emerging Science Group of the Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Is there protective immunity after an Omicron infection? November/December 2022 [cited 2023 Jan 11]

9. Bobrovitz N, et al. Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression. Lancet Infect Dis. 2023 Jan 18:S1473-3099(22)00801-5. doi: 10.1016/S1473-3099(22)00801-5. Epub ahead of print. PMID: 36681084.

10. Institut National de Santé Publique du Quebec. Administration of COVID-19 booster doses: Recommendations for winter and spring 2023. Available at https://www.inspq.qc.ca/en/publications/3284-covid-19-booster-doses-winter-spring-2023

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Eligibility

 

In B.C., individuals 6 months of age and older are eligible for COVID-19 vaccination. 


More information on how to get vaccinated in B.C. can be found on the Getting a Vaccine page. 
 
 
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COVID-19 mRNA vaccines (adult/adolescent)

Additional information specific to the mRNA vaccines currently authorized for use in Canada can be found in the Canadian Immunization Guide, COVID-19 vaccine.

 
Both the Pfizer-BioNTech Comirnaty® and Moderna Spikevax™ COVID-19 vaccines are mRNA vaccines.  Messenger RNA (mRNA) is the ‘blueprint’ that cells use to synthesize proteins required for our physiology. The COVID-19 mRNA vaccines use mRNA contained inside a lipid nanoparticle (LNP) that contains the synthetic nucleotide sequences that codes for the SARS-CoV-2 spike protein. After injection, the LNP is taken up by immune system cells, and once inside a cell, the mRNA provides the instructions that allow the cell to manufacture the spike protein. Once manufactured, the spike protein exits the cell, and becomes anchored onto the cell's surface. The immune system is activated to recognize the spike protein as foreign and initiates an immune response. The mRNA is then cleared by the cell’s natural mRNA degradation process. The estimated half-life for mRNA after injection is about 8-10 hours before degradation by native RNases (enzymes that break up the mRNA) in the body; the expressed spike protein persists in the body for several days and during this time continues to stimulate the immune response. mRNA vaccines are not live vaccines and cannot cause infection in the host. The delivered mRNA does not replicate, and does not enter the cell nucleus or interact with or alter the recipient’s DNA. 1, 2, 3     

Several mRNA vaccines are under development for other infections including cytomegalovirus, human metapneumovirus, parainfluenza virus type 3, Zika and influenza viruses.  

Manufacturing of mRNA vaccines has been under development for a decade. The process is cell-free (does not use human or other animal cells) and does not use vectors (like other viruses) or animal products, preservatives or adjuvants. 

 

1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. 2021 April 23 [cited 2021 April 28]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci.html

 

2. U.S. Food & Drug Administration [Internet]. Silver Spring (MD): U.S. Food & Drug Administration. 2020 meeting materials, vaccines and related biological products advisory committee December 10, 2020 meeting announcement. 2020 Dec 10 [cited 2021 Jan 5]. Available from: https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-december-10-2020-meeting-announcement

 

3. U.S. Food & Drug Administration [Internet]. Silver Spring (MD): U.S. Food & Drug Administration. 2020 meeting materials, vaccines and related biological products advisory committee December 17, 2020 meeting announcement. 2020 Dec 17 [cited 2021 Jan 5]. Available from: https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-december-17-2020-meeting-announcement

Efficacy

 

Efficacy of mRNA Vaccines based on initial clinical trials:

Although the original clinical trial data from 2020 for both mRNA vaccines estimated the vaccine efficacy against symptomatic COVID-19 to be between 91-95%, the effectiveness of these vaccines against symptomatic illness related to the subsequent variants has evolved.1, 2 

To review these data in details please see:

Efficacy and effectiveness of mRNA COVID-19 vaccines in the context of new and emerging variants:

Efficacy against symptomatic COVID-19 disease
Efficacy and effectiveness against symptomatic infection varies by variants. Protection against more severe COVID-19 outcomes is higher and better maintained over time. Clinical trials for monovalent COVID-19 vaccines were conducted prior to the emergence of Omicron, and have substantially lower vaccine effectiveness against symptomatic infection for Omicron and related variants due to partial immune escape. Vaccine effectiveness of bivalent Omicron-containing mRNA COVID-19 vaccines has yet to be established.3 

In clinical trials, the monovalent mRNA COVID-19 vaccines have been shown to be highly efficacious (approximately 74 to 95%) in the short term against confirmed symptomatic COVID-19 disease. There is similar efficacy in adults with 1 or more comorbidities, adolescents (12 to 15 years), younger adults and older adults.3

Studies have noted decreased protection against infection to occur over time with all COVID-19 vaccines including mRNA vaccines. Studies of vaccine efficacy against symptomatic infection after vaccination with the primary series suggest that protection with monovalent Moderna Spikevax may be more durable than with monovalent Pfizer-BioNTech Comirnaty vaccine. Furthermore, shorter intervals between the first and second dose of COVID-19 Vaccine series result in lower initial titres that may result in protection that decreases sooner.3, 4  

Efficacy and effectiveness against severe disease
The clinical trials of the authorized and available COVID-19 vaccines assessed efficacy against severe COVID-19 disease, but not all provided sufficient data to be able to assess the efficacy against hospitalizations or deaths.

Real world evidence suggests moderate to high vaccine effectiveness at preventing severe illness, such as hospitalization and death, which is sustained out to at least 6 months in most populations ages 12 years and more, including in older and frail populations. There is some decline noted in older adults (such as those 80 years of age and over) and residents in long term care homes in overall effectiveness over time, although protection against severe outcomes appears to be more durable than protection against infection.3

Effectiveness against hospitalization due to MIS-C
Real world evidence suggests the monovalent Pfizer-BioNTech Comirnaty COVID-19 vaccine has high vaccine effectiveness at preventing hospitalization due to MIS-C among adolescents 12 to 18 years of age. There are no results specific to other COVID-19 vaccines yet, however studies are ongoing.

Efficacy and effectiveness against asymptomatic infection 
Clinical trials for currently authorized COVID-19 vaccines were primarily designed to evaluate efficacy against symptomatic illness and conducted prior to the emergence of Omicron. Data on efficacy and effectiveness against asymptomatic infection remain limited. 
However, effectiveness studies have generally identified lower effectiveness against asymptomatic disease than symptomatic disease.3

Data on vaccine effectiveness against asymptomatic illness is limited as clinical trials for the authorized COVID-19 vaccines were primarily designed to evaluate efficacy against symptomatic illness which took place prior to the emergence of Omicron.  However, effectiveness studies have generally found that the effectiveness of COVID-19 vaccines against asymptomatic illness is lower than their effectiveness against symptomatic illness. 

 

‎For both mRNA vaccines, SARS-CoV-2 binding and neutralizing antibodies were both induced by one dose of the vaccine and boosted by the second dose of the vaccine. Immunity after the first dose was seen beginning at around day 10 with the Pfizer vaccine and day 14 following the Moderna vaccine. Maximal immune response was seen 7 days after the second dose for each vaccine.1, 5

 

 

‎1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. Appendix A. 2021 Jan 12 [cited 2021 Jan 13]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html


2. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. Appendix B. 2021 Jan 12 [cited 2021 Jan 13]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html


3. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide. COVID-19 vaccine. [updated 2022 Nov 18; cited 2022 Nov 18]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html


4. Skowronski DM, Setayeshgar S, Febriani Y, Ouakki M, Zou M, Talbot D, et al. Two-dose SARS-CoV-2 vaccine effectiveness with mixed schedules and extended dosing intervals: test-negative design studies from British Columbia and Quebec, Canada. medRxiv. 2021 Oct 26. doi: 10.1101/2021.10.26.21265397.


5. COVID-19 Immunization Task Force. COVID-19 Seroprevalence Report: Report #22. 2022.

Dosing and scheduling

Refer to the BC Immunization Manual Part 4 - Biological Products, COVID-19 vaccines for complete information on the COVID-19 mRNA vaccines prior to administration.

 
The schedules and doses for the primary series of COVID-19 mRNA vaccines for individuals 12 years of age and older are summarized in the COVID-19 Vaccine Eligibility table within the BC Immunization Manual. For product specific information refer to the BC Immunization Manual, Part 4 - Biological Products, COVID-19 Vaccines. 

The monovalent Moderna COVID-19 mRNA vaccine for individuals 6 years of age and older is no longer supplied in Canada as of April 2023. Furthermore, the current supply of monovalent mRNA vaccines in Canada will expire in summer of 2023. In light of this and the latest safety and immunogenicity data on the bivalent mRNA vaccines, NACI now recommends either a bivalent product or a monovalent product can be used for those 6 months of age and older for starting or completing a primary series. Informed consent should include a discussion that the Moderna Bivalent COVID-19 mRNA vaccine has not yet been approved for use in the primary series. Refer to the Bivalent COVID-19 mRNA vaccines section on this page for more information. 

 

NACI recommends if readily available (i.e., easily available at the time of vaccination without delay or vaccine wastage), the same COVID-19 mRNA vaccine product should be offered for the subsequent dose in a vaccine series started with a COVID-19 mRNA vaccine.1 


However, when the same COVID-19 mRNA product is not readily available, or is unknown, another COVID-19 mRNA vaccine product recommended for use in that age group can be considered interchangeable and should be offered to complete the vaccine series. Such a series should be considered as valid, without need to restart a two dose series with a new product.1 

Furthermore, monovalent and bivalent COVID-19 vaccines are interchangeable within the primary series. Refer to the Bivalent COVID-19 mRNA vaccines section on this page for more information.

 

1.  Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide. COVID-19 vaccine. [updated 2022 Nov 18; cited 2022 Nov 18]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html

Administration

 

Pain at the injection site is very common after the administration of the currently authorized COVID-19 mRNA vaccines, with more than 80% of recipients experiencing local injection site pain. Redness and swelling are also common.  Delayed local reactions including pain, redness, swelling, and occasionally pruritus, were observed in the Moderna clinical trials in about 1% of vaccine recipients, with onset on or after day 8 following vaccination. These delayed reactions were more likely to occur following the first dose than the second dose, and are thought to represent dermal hypersensitivity, typically resolving after 4-5 days. Vaccine recipients who have experienced these delayed local reactions have safely received the second dose.1, 2  These events are not reportable unless they meet the reporting criteria outlined in the BC Immunization Manual, Part 5: Adverse Events Following Immunization. ‎

 

 

1. Moderna. mRNA-1273 Sponsor Briefing Document [Internet]. Silver Spring (MD): FDA, Vaccines and Related Biological Products Advisory Committee; 2020 Dec 17 [cited 2021 February 22]. 83p. Available from: https://www.fda.gov/media/144452/download


2. Blumenthal KG, Freeman EE, Saff RR, et al. Delayed Large Local Reactions to mRNA1273 Vaccine against SARS-CoV-2. N Engl J Med. Published online March 3, 2021:NEJMc2102131. doi:10.1056/NEJMc2102131

Contraindications and precautions

 

Severe immediate allergic reactions such as anaphylaxis 

have been reported to be very rare following mRNA vaccination. As of October 22, 2021, NACI has made recommendations based on recent studies demonstrating that individuals who experienced anaphylaxis following their first dose of mRNA vaccine, were able to receive their second dose of mRNA vaccine with either mild or no side effects. NACI recommends that these individuals can safely receive future doses of mRNA vaccine provided there is:

  • consultation with an allergist or another appropriate physician before receiving future doses of a COVID-19 mRNA vaccine
  • a controlled setting where the vaccine can be administered with someone available who is experienced in managing anaphylaxis
  • an observation period of at least 30 minutes after vaccination (the normal observation period for people who have not experienced a severe immediate allergic reaction after vaccination is 15 minutes).
For a list of components in the vaccine and packaging consult the respective COVID-19 mRNA vaccine product monographs found at:

Pfizer-BioNTech: https://www.cvdvaccine.ca/

Moderna*: https://www.modernacovid19global.com/ca/


*The Moderna COVID-19 mRNA vaccine for 6 years of age and older is no longer supplied in Canada as of April 2023.

 

Both of the authorized COVID-19 mRNA vaccines in Canada contain polyethylene glycol (PEG) which can be found in various products such as: bowel preparation products for colonoscopy, laxatives, cough syrup, cosmetics, contact lens care solutions, skin care products and as an additive in some food and drinks. No cases of anaphylaxis to PEG in foods and drinks have been reported. ‎

 

 

In situations of suspected hypersensitivity or non-anaphylactic allergy to COVID-19 vaccine components, mRNA vaccination should be administered in a controlled setting with expertise and equipment to manage anaphylaxis, with an extended period of observation post-vaccination of at least 30 minutes.


For more information, refer to the BC Immunization Manual, Part 3 - Management of Anaphylaxis in a Non-Hospital Setting, Supervision of Vaccinee Post-immunization

 
Myocarditis is an inflammation of the heart muscle; if it is accompanied by pericarditis, an inflammation of the thin tissue surrounding the heart (the pericardium), it is referred to as myopericarditis. Symptoms can include shortness of breath, chest pain, or the feeling of a rapid or abnormal heart rhythm. Symptoms can be accompanied by abnormal tests (e.g., electrocardiogram, serum troponins, echocardiogram). These are inflammatory disorders of the outer lining of the heart and heart muscle, and occur for a variety of reasons including in association with viral infections.

As such, myocarditis can occur as a complication of COVID-19 infection. In Israel, COVID-19 infection has been estimated to cause myocarditis at a rate of 11 events per 100,000 persons among individuals aged 16 years and older. A retrospective study from the US found myocarditis (or pericarditis or myopericarditis) rates after primary COVID-19 infection to be as high as 45 cases per 100,000 patients in young males aged 12-17 years.  


Myocarditis/pericarditis following COVID-19 mRNA vaccines remains a rare adverse event following immunization (defined by the Canadian Immunization Guide as occurring at a frequency of 1 per 10,000 cases to less than 1 per 1,000 cases), even among the age groups where the highest rates of this event have been observed.1 Canadian data continue to show that with the primary series, the incidence of myocarditis is rare with either mRNA vaccine, but higher following the Moderna 100 mcg vaccine compared to the Pfizer-BioNTech 30 mcg vaccine. In Canada, as of April 15, 2022, the overall reported rate of myocarditis/pericarditis was 1.7 per 100,000 doses administered following any dose of the Moderna 100 mcg vaccine compared to 1.1 per 100,000 doses administered following any dose of the Pfizer-BioNTech 30 mcg vaccine. The reported rates of myocarditis/pericarditis within 7 days among males 18-29 years after the second vaccine dose were 16.36 per 100,000 for the Moderna 100 mcg vaccine and 3.14 per 100,000 for the Pfizer-BioNTech 30 mcg vaccine. These events are reported more frequently after the second dose and have been observed mostly in males 12-29 years of age, usually within a week of vaccination. Most cases have been mild and resolved quickly. 

Most cases recover fully with conservative treatment, with no serious outcomes. In BC, we have ensured that health care providers are aware of this observation and the possibility of it being causally linked to the vaccine, and how to diagnose and report this event when it occurs after mRNA vaccine. This is an emerging safety signal and will need to be studied further. 

Subsequent doses of COVID-19 mRNA vaccine should be deferred in those who experienced a physician-diagnosed myocarditis or pericarditis event following a dose of an mRNA vaccine with no other cause identified, until further information about the risk of recurrence is available. 

NACI recommends for those with a history compatible with pericarditis and who either had no cardiac workup or had normal cardiac investigations, can receive the next dose once they are symptom free and at least 90 days has passed since vaccination.2

For individuals with confirmed myocarditis (with or without pericarditis) after a dose of an mRNA COVID-19 vaccine who choose to receive another dose of vaccine, NACI recommends to discuss the risks and benefits of this with their healthcare provider. If another dose of the vaccine is offered, it should be Pfizer–BioNTech Comirnaty 30 mcg vaccine due to the lower rate of myocarditis and or pericarditis compared to Moderna Spikevax 100 mcg vaccine. Furthermore,  informed consent should emphasize the unknown risk of recurrence of myocarditis and/or pericarditis for these individuals and the importance of seeking immediate medical assessment and care should these symptoms develop.2 

Deferral is not required for those with a prior history of myocarditis or pericarditis that is unrelated to COVID-19 mRNA vaccines and are no longer being followed by a medical professional for heart issues.

To review the latest numbers of myocarditis and pericarditis cases reported in BC refer to B.C.’s reports on adverse events.

 

1.  Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Updated recommendation on the use of authorized COVID-19 vaccines in individuals aged 12 years and older in the context of myocarditis and pericarditis reported following mRNA COVID-19 vaccines. Public Health Agency of Canada. 2021 December 3 [cited 2022 November 10] Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/rapid-response-recommendation-use-covid-19-vaccines-individuals-aged-12-years-older-myocarditis-pericarditis-reported-following-mrna-vaccines.html


2. ‎ Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Summary of NACI advice on vaccination with COVID-19 vaccines following myocarditis (with or without pericarditis). Public Health Agency of Canada. 2022 January 14 [cited 2022 November 29] Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/summary-advice-vaccination-covid-19-vaccines-following-myocarditis-with-without-pericarditis.html


Vaccine storage and handling

 
The mRNA vaccines do not contain a preservative to prevent microbial contamination following first vial puncture or dilution and therefore they must be used within the specified periods of time indicated below.
  • All presentations of the monovalent and bivalent Pfizer-BioNTech COVID-19 mRNA vaccines must be used within 12 hours of first vial puncture or dilution (and kept between +2°C to +25°C)
  • All presentations of the monovalent and bivalent Moderna COVID-19 mRNA vaccines must be used within 24 hours of first vial puncture (and kept at room temperature up to +25°C)

 

Vaccine storage and handling information for the mRNA vaccines can be found on the manufacturer's websites:

*The monovalent Moderna COVID-19 mRNA vaccine for 6 years of age and older is no longere supplied in Canada as of April 2023.


For more information specific to receiving and handling the Pfizer-BioNTech and Moderna vaccines, refer to the BC Immunization Manual, Appendix E - Management of Biologicals, Guidance for Receiving and Handling the Pfizer-BioNTech COVID-19 mRNA vaccine (including dry ice procedures) and Guidance for Receiving and Handling the Moderna COVID-19 mRNA Vaccine. Additional information, including standard operating procedures can be found on the COVID-19 Immunize BC Operations Centre: Standard Operating Procedures page. 

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Bivalent COVID-19 mRNA vaccines

 
Bivalent COVID-19 mRNA vaccines are modified versions of the monovalent COVID-19 mRNA vaccines. The bivalent COVID-19 mRNA vaccines target the spike proteins found in both the ancestral (original) strain of SARS-CoV-2 and the Omicron variant.   

On October 7, 2022, Health Canada authorized the use of the Pfizer-BioNTech Comirnaty® Bivalent COVID-19 mRNA vaccine [Original and Omicron BA.4/BA.5] as a booster dose for individuals 12 years of age and older.1

On December 9, 2022, Health Canada authorized the use of the Pfizer-BioNTech Comirnaty® Bivalent COVID-19 mRNA vaccine [Original and Omicron BA.4/BA.5] as a booster dose for individuals 5 to 11 years of age.2 

On November 3, 2022, Health Canada authorized the use of the Moderna Spikevax™ Bivalent COVID-19 mRNA vaccine [Original and Omicron B.1.1.529 (BA.4/5) Variant] as a booster dose for individuals 18 years of age and older. As of May 18, 2023, Moderna Spikevax™ Bivalent COVID mRNA vaccine [Original and Omicron B.1.1.529 (BA.4/5) Variant] is now authorized for use as a booster dose in those 6 years of age and older.

On June 9, 2023, NACI recommended that bivalent COVID-19 mRNA vaccines can be used for the primary series. This decision is based on the available immunogenicity and safety data on the bivalent COVID-19 mRNA vaccines and the anticipation that the current supply of original monovalent COVID-19 mRNA vaccines will expire in the coming months.3  Use of the Moderna bivalent vaccine for the primary series in those 6 months of age and older is off-label and informed consent should include a discussion that this product has not yet been approved for use in the primary series or for use in those 6 months to 5 years of age.

For a visual comparison of all COVID-19 mRNA vaccines supplied in BC, refer to the COVID-19 mRNA Vaccine Comparison Table.

For more information and details on storage and handling for each vaccine refer to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 Vaccines.

For more information on eligibility criteria for bivalent COVID-19 mRNA vaccines see the Booster doses section on this page.

 
With the emergence of the highly transmissible Omicron variant and its subvariants in the summer of 2022, a resurgence of COVID-19 cases has been seen worldwide.1  This trend started with BA.1 emerging as one of the most antigenically distinct subvariants. Several sublineages within Omicron (BA.1, BA.2, BA.3, BA.4, BA.5 and XBB) have been identified, which share many of the same spike protein mutations. As a result, the Omicron variants have demonstrated partial evasion of immunity attained by the monovalent COVID-19 vaccines or by a previous infection with a SARS-CoV-2 variant that emerged prior to Omicron.4  Although a booster dose of a monovalent COVID-19 vaccine appears to restore protection against severe disease and death against currently circulating variants, there has been substantial virus evolution since the first cases of COVID-19. Evolution of the SARS-CoV-2 virus is likely to continue, resulting in the emergence of new variants in the future. In this context, vaccination with a broad range of SARS-CoV-2 spike protein antigens may be beneficial to retain and potentially improve protection against future variants.5  

The current data suggests that all Omicron-containing COVID-19 vaccines induce a stronger and more robust immune response to the Omicron Variants of Concern (VOC) and sublineages compared to monovalent mRNA vaccines. Hence, moving foward a bivalent COVID-19 vaccine is the preferred vaccine product for booster doses for eligible individuals.  

Based on varying supply of monovalent and bivalent COVID-19 vaccines and the anticipation there will be no supply of original monovalent COVID-19 mRNA vaccines in the coming months, there is no preferential recommendation between monovalent or bivalent COVID-19 vaccines in the primary series. Bivalent  COVID-19  mRNA vaccines and monovalent COVID-19 mRNA vaccines are interchangeable for use in starting or completing the primary series in individuals 6 months of age and older.

 

Bivalent COVID-19 mRNA vaccines are the preferred products to be used as booster doses. Individuals 12 years of age and older are eligible to receive a bivalent BA.4/5 COVID-19 mRNA vaccine booster regardless of the number of booster doses previously received. Individuals 5 to 11 years of age are also eligible for a booster dose of a bivalent BA.4/5 COVID-19 mRNA vaccine. 


The Moderna bivalent COVID-19 vaccine is the preferred product to be used in the primary series or for booster doses for those who are moderately to severely immunosuppressed, as Moderna COVID-19 vaccine may induce a greater immune response compared to the Pfizer-BioNTech COVID-19 vaccine. Real-world evidence from adult populations (≥18 years of age) suggest that after a two dose primary series, monovalent Moderna Spikevax (100 mcg) may have resulted in higher VE compared to monovalent Pfizer-BioNTech Comirnaty (30 mcg) and is associated with a higher seroconversion rate among adult immunocompromised patients. Booster vaccination with monovalent Moderna Spikevax (50 mcg) was also found to be more effective than monovalent Pfizer-BioNTech Comirnaty (30 mcg) within the first 12 weeks following vaccination, during a period of Delta followed by Omicron variant dominance.1


NACI is currently only recommending one booster dose after the primary series for individuals 5-11 years of age. However, at the provider’s discretion, an additional bivalent booster dose (as per recommended interval) could be offered to individuals considered at high risk of severe COVID-19 who have previously received a booster dose with the monovalent Pfizer-BioNTech COVID-19 mRNA vaccine.2 For other individuals 5-11 years of age, the bivalent vaccine is not recommended if a monovalent booster has already been received, but may be provided upon parent/guardian request.  

For specific recommendation for the use of COVID-19 vaccines see the COVID-19 Vaccine Eligibility table. 

For product specific information for bivalent COVID-19 mRNA vaccines see the BC Immunization Manual, Part 4- Biological Products, COVID-19 Vaccines. 

 
Yes. On June 9, 2023, NACI recommended that bivalent COVID-19 mRNA vaccines can be used in the primary series. Use of the Moderna bivalent vaccine for the primary series in those 6 months of age and older is off-label and informed consent should include a discussion that this product has not yet been approved for use in the primary series or for use in those 6 months to 5 years of age.

NACI supports this recommendation based on the available data on use of bivalent products as booster doses as well as clinical studies completed for those 6 month to 5 years of age.

The surveillance data from Canada and  the US found the safety profile of the bivalent mRNA COVID-19 vaccines boosters to be similar to original mRNA COVID-19 vaccine boosters.6, 7, 8  A Danish cohort study evaluated the association of bivalent Omicron-containing mRNA booster vaccination as a fourth dose in those 50 years of age and older. This study assessed 27 different adverse events in a sample of 1,740,417 individuals and concluded that bivalent Omicron-containing mRNA booster vaccination as a fourth dose was not associated with increased risk for these adverse events.9   

The real-world effectiveness data suggest that children and adults who received a bivalent BA.4/5 mRNA vaccine for a booster dose had increased protection against infection, symptomatic disease and severe outcomes compared to those who only received the monovalent COVID-19 mRNA vaccines in the past.10, 11,12  Omicron and its sub-lineages that are currently the dominant strains in Canada are some of the most antigenically distinct sub-lineages seen to date. The bivalent vaccine products enables expansion of immune repertoire against COVID-19 infections which will be beneficial in the long term. This is especially important for individuals who have not been infected by SARS-CoV-2 or have not received prior COVID-19 vaccines as it maximizes the breadth of immunity at the earliest opportunity.3 This would especially be important for infants aging into 6 months of age for eligibility for COVID-19 vaccines who most likely do not have prior SARS-CoV-2 infection.

The immunogenicity and safety of Moderna bivalent BA.1 as a primary series was evaluated in a phase 3 open-label study in 179 unvaccinated children 6 months to 5 years of age. In this study the antibody response 28 days after dose 2 for the BA.1 vaccine was superior to that of the original Moderna vaccine. This study also showed that local and systemic reactions after dose 1 and dose 2 of the bivalent vaccine were similar to the original Moderna vaccine. Although, Moderna Bivalent BA.1 COVID-19 vaccine is no longer available in Canada, these findings could be indirectly applied to Moderna BA.4/5 products.

NACI also indicated that as most of the supply of the original monovalent formulations of the mRNA vaccines will be expiring in the summer of 2023, recommending these vaccines for the primary series would not be feasible. NACI emphasized that this recommendation ensures access to vaccine supply particularly for infants who will be aging into vaccine eligibility at 6 months and are less likely to have prior infection. 
 

 

Yes. COVID-19 vaccines may be given concomitantly with (i.e., same day), or at any time before or after non-COVID-19 vaccines

(including live and non-live vaccines). If more than one vaccine is administered at a single visit, they should be administered at different injection sites.


Co-administration of COVID-19 vaccines with other vaccines is in accordance with NACI recommendations, general best practices for immunization, and is supported by the US Center for Disease Control and Prevention and the World Health Organization. 

Data from recent studies also support the co-administration of COVID-19 and influenza vaccines. These studies have found co-administration to be safe and the immune response towards all influenza strains and the SARS-CoV-2 spike protein with co-administration is generally non-inferior to that seen when either vaccine is administered alone.13-19  There are also data to support the co-administration of COVID-19 vaccine and pneumococcal polysaccharide 23 vaccine.6 The overall rate of solicited local and systemic adverse events was similar between subjects who received COVID-19 and influenza vaccine and those who received the COVID-19 vaccine alone. The adverse events reported were mostly mild-to-moderate and self-limiting.20 

Co-administration recommendations have been provided by Public Health in other countries, including Italy, France, Germany, Spain, Finland, the UK, Russia, and Australia.12  Co-administration has several potential benefits, including improved patient convenience and compliance, simplified immunization schedules, fewer missed opportunities to vaccinate, reduced costs, and logistical 
advantages.20
 

 
Clinical trial data for Moderna Spikevax BA.1 Bivalent (50 mcg) administered as a second booster dose to individuals ≥18 years of age had a similar reactogenicity profile to that of monovalent Moderna Spikevax (50 mcg) given as a second booster dose. Also, the frequency of adverse events following Moderna Spikevax BA.1 Bivalent (50 mcg) given as a second booster dose was similar or lower compared to that of a first booster dose of monovalent 
Moderna Spikevax (50 mcg), and of the second dose of the monvalent Moderna Spikevax primary series (100 mcg). There were no vaccine-related cases of myocarditis, pericarditis or deaths reported during the study period. No new safety signals were identified with Moderna Spikevax BA.1 Bivalent (50 mcg). However, given the number of participants enrolled in the bivalent clinical trial, it is unlikely that rare adverse events would be detected.20

There are no clinical safety data currently available for Pfizer-BioNTech Comirnaty BA.4/5 Bivalent (30 mcg) specifically; however, the clinical and post-market safety data from Pfizer-BioNTech Comirnaty BA.1 Bivalent and monovalent Comirnaty, respectively suggest that Pfizer-BioNTech Comirnaty BA.4/5 Bivalent (30 mcg) will likely be well tolerated with a similar safety profile to monovalent Comirnaty (30 mcg) and Comirnaty BA.1 Bivalent (30 mcg), when used as a booster dose. Data from the Pfizer-BioNTech Comirnaty BA.1 Bivalent vaccine candidate clinical trial demonstrated that Pfizer-BioNTech Comirnaty BA.1 Bivalent (30 mcg) had a similar reactogenicity profile as monovalent Comirnaty (30 mcg), when administered as a fourth dose to individuals >55 years of age. There were no vaccine-related cases of myocarditis, pericarditis or deaths reported with the use of Pfizer-BioNTech Comirnaty BA.1 Bivalent (30 mcg), and no new safety signals were identified.21

However, given the number of participants enrolled in the Moderna Spikevax BA.1 Bivalent (50 mcg) and Pfizer-BioNTech Comirnaty BA.1 Bivalent (30 mcg) clinical trials, it is unlikely that rare adverse events would be detected.21

The regulatory review process leveraged preliminary clinical trial data on the Pfizer Bivalent BA.4/5 vaccine (30 mcg) in adolescents and adults ≥12 years of age, clinical trial data on the use of the Pfizer Bivalent BA.1 (30 mcg) and monovalent Pfizer Omicron BA.1 vaccines in adults, as well as immunogenicity and safety data of monovalent Pfizer-BioNTech Comirnaty vaccine (10 mcg) in individuals 5 to 11 years of age.2

Based on the available post-marketing safety data from Canada and internationally, the safety profile of the bivalent COVID-19 mRNA vaccine boosters is comparable to that of the original COVID-19 mRNA vaccine boosters among individuals aged ≥5 years.21  

A possible association between Pfizer-BioNTech Comirnaty bivalent BA.4/5 booster and ischemic stroke in persons ≥65 years of age has been identified by the US Vaccine Safety Datalink (VSD). However, this possible association has not been replicated in other surveillance systems used to monitor vaccine safety in the US or in other countries. For Moderna Spikevax bivalent BA.4/5 COVID-19 mRNA vaccine, this signal has not been observed. Currently, the totality of US data and international data including from Canada, Israel, Europe, and Singapore suggest that it is very unlikely that the potential signal in the VSD represents a true clinical risk. Monitoring of this potential safety signal is ongoing.22, 23  

 

There is no longer a preferential recommendation for the use of Pfizer-BioNTech COVID-19 vaccine as a booster dose in those 18-29 years of age due to increased risk of myocarditis. Per NACI, post-market safety surveillance data to date indicate that the risk of myocarditis following a booster dose is lower compared to that following the second dose in the primary series, and current data do not show a product-specific difference in the risks of myocarditis and/or pericarditis after a booster dose of a COVID-19 mRNA

vaccine. Individuals in this age group can receive a booster dose with any available COVID-19 mRNA vaccine for which they are currently eligible.4‎

 

 
1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated guidance on COVID-19 vaccine booster doses in Canada. 2022 Oct 7 [cited 2022 Oct 12]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/guidance-covid-19-vaccine-booster-doses.pdf

2. Public Health Agency of Canada [Internet] Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated recommendations on the use of COVID-19 vaccine booster doses in children 5 to 11 years of age and concurrent vaccine administration. 2022 Dec 9 [cited 2022 Dec 9]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/updated-recommendations-use-covid-19-vaccine-booster-doses-children-5-11-years-concurrent-administration.pdf

3. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Interim guidance on the use of bivalent Omicron-containing COVID-19 vaccines for primary series. 2023 Jun 9 [cited 2023 Jul 17]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-interim-guidance-use-bivalent-omicron-containing-covid-19-vaccines-primary-series/naci-statement-bivalent-primary-series.pdf

4. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Recommendations on the use of bivalent Omicron-containing mRNA COVID-19 vaccines. 2022 Sept 1 [cited 2022 Sept 9]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-bivalent-Omicron-containing-mrna-covid-19-vaccines.pdf.

5. Interim statement on the composition of current COVID-19 vaccines [Internet]. Geneva (CH): World Health Organization (WHO); 2022 Jun 17 [cited 2022 Aug 10]. Available from: https://www.who.int/news/item/17-06-2022-interim-statement-on--the-composition-of-currentCOVID-19-vaccines. 

6. Public Health Agency of Canada. Reported side effects following COVID-19 vaccination in Canada. Data cut-off Mar 3, 2023 [Internet]. Ottawa (ON): Health Canada; 2023 Mar 17 [cited

7. Ontario Agency for Health Protection and Promotion (Public Health Ontario). Adverse Events Following Immunization (AEFIs) for COVID-19 in Ontario: December 13, 2020 to April 23, 2023. Data cut-off Apr 23, 2023 [Internet]. Toronto (ON): King's Printer for Ontario; 2023 Apr 23 [cited 2023 Jul 17]. Available from:
https://www.publichealthontario.ca/-/media/Documents/nCoV/epi/covid-19-aefireport.pdf?sc_lang=en.

8. Shimabukuro T. COVID-19 vaccine safety update: Primary series in young children and booster doses in older children and adults [slides presented at Advisory Committee on Immunization Practices (ACIP) meeting September 1, 2022] [Internet]. Atlanta (GA): Centers for Disease Control and Prevention (CDC); 2022 Sep 01 [cited 2023 Jul 17]. Available from:

9. Andersson NW, Thiesson EM, Vinsløv Hansen J, Hviid A. Safety of bivalent omicroncontaining mRNA-booster vaccines: a nationwide cohort study. medRxiv. 2023 Jan 22. https://doi.org/10.1101/2023.01.21.23284855.
  
10. Tenforde MW, Weber ZA, Natarajan K, Klein NP, Kharbanda AB, Stenehjem E, et al. Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19-Associated Emergency Department or Urgent Care Encounters and Hospitalizations Among Immunocompetent Adults - VISION Network, Nine States, September-November 2022. MMWR Morb Mortal Wkly Rep. 2022 Dec 30;71(5152):1616,1624. doi: 10.15585/mmwr.mm715152e1
  
11. Surie D, DeCuir J, Zhu Y, Gaglani M, Ginde AA, Douin DJ, et al. Early Estimates of Bivalent mRNA Vaccine Effectiveness in Preventing COVID-19-Associated Hospitalization Among Immunocompetent Adults Aged ≥65 Years - IVY Network, 18 States, September 8-November 30, 2022. MMWR Morb Mortal Wkly Rep. 2022 Dec 30;71(5152):1625,1630.  doi:10.15585/mmwr.mm715152e2

12. Lin D, Xu Y, Gu Y, Zeng D, Wheeler B, Young H, et al. Effectiveness of Bivalent Boosters against Severe Omicron Infection. N Engl J Med. 2023 Feb 23. doi:10.1056/NEJMc2215471.


13. Chen H, Huang Z, Chang S, Hu M, Lu Q, Zhang Y, Wang H, Xiao Y, Ge Y, Zou Y, Cui F. Immunogenicity and safety of an inactivated SARS-CoV-2 vaccine (Sinopharm BBIBP-CorV) coadministered with quadrivalent split-virion inactivated influenza vaccine and 23-valent pneumococcal polysaccharide vaccine in China: A multicentre, non-inferiority, open-label, randomised, controlled, phase 4 trial. Vaccine. 2022 Aug 26;40(36):5322-32. Available from: https://doi.org/10.1016/j.vaccine.2022.07.033  


14. Izikson R, Brune D, Bolduc JS, Bourron P, Fournier M, Moore TM, Pandey A, Perez L, Sater N, Shrestha A, Wague S. Safety and immunogenicity of a high-dose quadrivalent influenza vaccine administered concomitantly with a third dose of the mRNA-1273 SARS-CoV-2 vaccine in adults aged≥ 65 years: a phase 2, randomised, open-label study. The Lancet Respiratory Medicine. 2022 Apr 1;10(4):392-402. Available from: https://doi.org/10.1016/S2213-2600(21)00557-9


15. Lazarus R, Baos S, Cappel-Porter H, Carson-Stevens A, Clout M, Culliford L, Emmett SR, Garstang J, Gbadamoshi L, Hallis B, Harris RA. Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. The Lancet. 2021 Dec 18;398(10318):2277-87. Available from: https://doi.org/10.1016/S0140-6736(21)02329-1


16. Toback S, Galiza E, Cosgrove C, Galloway J, Goodman AL, Swift PA, Rajaram S, Graves-Jones A, Edelman J, Burns F, Minassian AM. Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccines: an exploratory substudy of a randomised, observer-blinded, placebo-controlled, phase 3 trial. The Lancet Respiratory Medicine. 2022 Feb 1;10(2):167-79. Available from: https://doi.org/10.1016/S2213-2600(21)00409-4 


17. Janssen C, Mosnier A, Gavazzi G, Combadière B, Crepey P, Gaillat J, Launay O, Botelho-Nevers E. Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. Human Vaccines & Immunotherapeutics. 2022 Oct 14:2131166. Available from: https://doi.org/10.1080/21645515.2022.2131166


18. Shenyu W, Xiaoqian D, Bo C, Xuan D, Zeng W, Hangjie Z, Qianhui Z, Zhenzhen L, Chuanfu Y, Juan Y, Gang Z. Immunogenicity and safety of a SARS-CoV-2 inactivated vaccine (CoronaVac) co-administered with an inactivated quadrivalent influenza vaccine: A randomized, open-label, controlled study in healthy adults aged 18 to 59 years in China. Vaccine. 2022 Aug 26;40(36):5356-65. Available from: https://doi.org/10.1016/j.vaccine.2022.07.021


19. Domnich A, Orsi A, Trombetta CS, Guarona G, Panatto D, Icardi G. COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy. Pharmaceuticals. 2022 Mar 8;15(3):322. Available from: https://doi.org/10.3390/ph15030322


20. Public Health Agency of Canada [Internet]. Ottawa (ON); Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated guidance on COVID-19 vaccine booster doses in Canada . 2022 October 7 [Cited 2022 Nov 16]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/guidance-covid-19-vaccine-booster-doses.pdf


21. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization. Guidance on an additional COVID-19 booster dose in the spring of 2023 for individuals at high risk of severe illness due to COVID-19. 2023 Mar 3 {cited 2023 Mar 7]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-guidance-additional-covid-19-booster-dose-spring-2023-individuals-high-risk-severe-illness-due-covid-19/statement.pdf


22. Shimabukuro T, Klein, N. COVID-19 mRNA bivalent booster vaccine safety [slides presented at Vaccines and Related Biological Products Advisory Committee (VRBPAC) meeting January 26, 2023] [Internet]. Silver Spring (MD): Food and Drug Administration (FDA); 2023 Jan 26 [cited 2023 Mar 20]. Available from: https://www.fda.gov/media/164811/download.

23. CDC & FDA Identify Preliminary COVID-19 Vaccine Safety Signal for Persons Aged 65 Years and Older [Internet]. Atlanta (GA): Centers for Disease Control and Prevention (CDC); 2023 Jan 13 [cited 2023 Mar 20]. Available from: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/bivalent-boosters.html.
 

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Booster doses

 
While vaccine effectiveness (VE) against SARS-CoV-2 infection following the completion of a primary series was originally demonstrated to be high (>90%) against the original strain and earlier variants (e.g., Delta), VE against Omicron infection and symptomatic disease after an mRNA primary series is substantially lower and decreases with time from the second dose; protection is minimal by six months since the second dose in adults.  

VE in adults against infection/symptomatic disease for Omicron from a booster dose of mRNA vaccine is approximately 65% and in most studies, decreases over time since vaccination. Vaccine protection in adults against severe disease and hospitalization due to COVID-19 has been more durable than protection against symptomatic disease or infection, and is approximately 10 to 20% higher following a third dose (or first booster) reaching approximately 90% or more compared to those who have only completed a primary series. There are emerging data on the VE of a booster dose against infection/symptomatic disease over time in adolescents showing similar trends as observed in adults.

For the latest recommendations for booster doses in BC refer to the COVID-19 Vaccine Eligibility.
 

 
Booster doses improve the immune response and vaccine effectiveness that has decreased over time. Against Omicron, a booster dose increased protection compared to pre-booster levels, with protection against infection/symptomatic disease at approximately 60%. Protection against severe disease is at around 90%, and generally remained above 70% for approximately 6 months post booster dose. Subsequent booster doses raise protection again, but waning continues to occur, particularly against infection/symptomatic disease.1 

Real-world effectiveness data from the US suggest that in adults, a booster dose of a BA.4/5 bivalent mRNA COVID-19 vaccine provides increased protection against both symptomatic disease and hospitalization, compared to those who did not receive a bivalent booster dose but received at least 2 previous doses of original monovalent vaccines in the past.

NACI emphasizes that all Omicron-containing COVID-19 vaccines have been shown to induce stronger and more robust immune response to Omicron VOC and sublineages compared to original monovalent mRNA vaccines and are expected to provide protection against severe outcome from COVID-19.1  Data from Ontario, the US, and some Scandinavian countries support this finding.2-6
However, as more time has lapsed since the last dose, the waning immunity may contribute to lower vaccine effectiveness (VE) in this group.5 


 
For the latest COVID-19 booster recommendation see COVID-19 Vaccine Eligibility.

The COVID-19 risk over the summer is expected to remain low, with respiratory illnesses typically increasing in the fall and winter months. It is important to discuss with clients presenting for a booster dose over the summer, that receipt of the vaccine will likely delay their next dose (i.e., Fall 2023 booster) due to the recommended interval between doses. There will be a new formulation of COVID-19 vaccine available in the fall to provide better protection against current circulating variants.  

NACI has recommended a dose of the new formulation COVID-19 vaccine for those in the authorized age groups for the fall of 2023. Manufacturers have indicated that new formulation of COVID-19 vaccine is in development and products are forthcoming. Further information about the fall 2023 dose will be available soon. 

 
The spring 2023 booster dose recommendations were based on the evidence that age remains a very important risk factor for severe illness from COVID-19 as the risk of hospitalization and intensive care admission increases with age.3  In addition, evidence suggests that hybrid immunity, achieved by vaccination and infection, may provide superior protection compared to vaccination or infection alone. Hybrid immunity differs by age group in Canada, with many adolescents and young adults having hybrid immunity, and a larger proportion of older adults being protected by vaccination only.

Recent vaccine effectiveness studies show greater waning of protection against hospitalizations in older adults who have been vaccinated but do not have hybrid immunity (because they have not been infected). Epidemiological modelling based on these studies indicate that an additional spring booster dose in in older adults may be able to prevent hundreds or thousands of hospitalizations in Canada this year. 

 
NACI recommends the spring 2023 booster dose can be provided at a recommended interval of 6 months or more  from the last dose of COVID-19 vaccine or SARS-CoV-2 infection, which ever is most recent. Antibody response is higher with longer intervals between doses of vaccine as well as between infection and vaccine.

A 5 month minium interval can be used between a previous dose of COVID-19 vaccine and a booster dose for exceptional circumstances such as travel or other unique considerations (e.g., a scheduled start of immune compromising therapy). Other unique situations may include, but are not limited to, operational considerations (e.g., scheduling clinics within longterm care facilities) or clinical discretion. 

While COVID-19 vaccine can be offered to individuals at any time following recovery from SARS-CoV-2 infection without contraindication, individuals who have had at least 2 doses of mRNA vaccine and have had a COVID-19 infection are well protected against serious disease and hospitalization. However, for those who wish to receive an additional dose of vaccine, an interval of 6 months is recommended between vaccine or infection whichever was more recent. This recommendation is based on the emerging evidence on hybrid immunity and the superior protection it provides against COVID-19.

More information on hybrid immunity can be found on this page under General questions, What is hybrid Immunity?

 
Canadian and International safety surveillance data suggest that the reactogenicity for first and second booster doses is comparable to the reactogenicity of the primary series. Overall, booster doses were well tolerated and no new safety signal was identified.

The risk for myocarditis and/or pericarditis following the first booster dose was lower compared to dose 2 of the primary series, which is also consistent with an extended interval between doses. Similarly,  the risk of myocarditis and/or pericarditis associated with a second booster dose of a monovalent COVID-19 vaccine is lower than the risk following the second dose of the primary series.1 

 

Reformulations of previously recommended mRNA vaccines may be offered to pregnant or breastfeeding individuals without contraindications to the vaccine, based on reassuring published data regarding the safety of mRNA vaccines in pregnancy.7 

Pregnancy is a higher risk period for complications from COVID-19 infection, and pregnant people are more likely to be hospitalized and admitted to intensive care compared to their non-pregnant age-matched peers.  

Optimizing immunity against COVID-19 during pregnancy is desirable because serious illness during pregnancy can put both the pregnant person and the fetus at risk and may result in preterm birth, still birth or Caesarian section. COVID-19 immunization during pregnancy is safe for the pregnant person and for the fetus. No specific safety signals have been detected related to pregnancy.

Although, the primary indication for administration of COVID-19 vaccination is for maternal protection, IgG antibodies from the pregnant person are transferred to the fetus. This provides passive immunity to the newborn, which may reduce the risk of infection for the infant during their first several months of life.

NACI recommends that a bivalent COVID-19 booster dose should be offered at any stage of pregnancy regardless of the number of monovalent booster doses previously received. Similar to other groups, this dose may be offered at an interval of 6 months since a previous COVID-19 vaccine dose.7 

Individuals who are breastfeeding may be offered a bivalent 
COVID-19 booster dose, regardless of the number of monovalent
booster doses previously received.

 
1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide: COVID-19 Vaccine. 2023 March 22 [cited 2023 Mar 31]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html 

2. Lin D, Xu Y, Gu Y, Zeng D, Wheeler B, Young H, et al. Effectiveness of Bivalent Boosters against Severe Omicron Infection. N Engl J Med. 2023 Jan 25. doi: 10.1056/NEJMc2215471.

3. Lin D, Xu Y, Gu Y, Zeng D, Wheeler B, Young H, et al. Effectiveness of Vaccination and Previous Infection Against Omicron Infection and Severe Outcomes in Children Under 12 Years of Age. medRxiv. 2023 Jan 19. https://doi.org/10.1101/2023.01.18.23284739.

4. Kwong J, CIRN PCN Ontario team. Personal communication. Effectiveness of monovalent and bivalent mRNA COVID-19 vaccine booster doses against Omicron severe outcomes. 2022 Dec 12.

5. Andersson NW, Thiesson EM, Baum U, Pihlström N, Starrfelt J, Faksová K, et al. Comparative effectiveness of the bivalent BA.4-5 and BA.1 mRNA-booster vaccines in the Nordic countries. medRxiv. 2023 Jan 19. https://doi.org/10.1101/2023.01.19.23284764.

6. Lee IT, Cosgrove CA, Moore P, Bethune C, Nally R, Bula M, et al. A Randomized Trial Comparing Omicron-Containing Boosters with the Original Covid-19 Vaccine mRNA-1273. medRxiv. 2023 Jan 24. https://doi.org/10.1101/2023.01.24.23284869

7. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated guidance on COVID-19 vaccines for individuals who are pregnant or breastfeeding. 2022 Sep 9 [cited 2022 Sep 12]. Available from:

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COVID-19 mRNA vaccines for children 5-11 years

Refer to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 vaccines for complete information on the COVID-19 mRNA vaccines prior to administration.

 
On November 19, 2021 Health Canada approved the monovalent Pfizer-BioNTech COVID-19 vaccine  (COMIRNATY®, 10 mcg) for use in children 5-11 years of age. Moderna's monovalent COVID-19 vaccine (SPIKEVAXTM, 50 mcg) was approved for use in children 6-11 years of age on March 17, 2022 and on July 13, 2022 the Moderna (25 mcg) formulation was approved for children 6 months to 5 years of age. However, the monovalent Moderna COVID-19 mRNA vaccine for 6 years of age and older is no longer supplied in Canada as of April 2023. 

On June 9, 2023, NACI recommended bivalent COVID-19 mRNA vaccines can be used for the primary series for those 6 months of age and older. Use of the Moderna bivalent vaccine for the primary series in those 6 months of age and older is off-label and informed consent should include a discussion that this product has not yet been approved for use in the primary series or for use in those 6 months to 5 years of age.1 

The National Advisory Committee on Immunization (NACI) recommends that a complete series of COVID-19 mRNA vaccine should be offered to children in the authorized age group who do not have contraindications to the vaccine, with a dosing interval of at least 8 weeks between the first and second dose. 

 
While most children do not become severely ill with COVID-19 disease, rarely some children may develop severe COVID-19 disease and require hospitalization. 

Children are also at risk of developing multisystem inflammatory syndrome in children (MIS-C), following infection with the SARS-CoV-2 virus. MIS-C is a rare but serious event that can occur several weeks following infection. As of July 23, 2022, there have been a total of 32 cases of MIS-C in BC with a median age of 9 years (range from 4 months to 16 years of age).2

Children may also be at risk of a post COVID-19 condition known as long COVID or post-acute COVID-19 syndrome. While evidence is limited in pediatric populations, current evidence suggests the risk is lower in children compared to older age groups.

The Omicron variants may pose a higher risk of infection for children due to their increased transmissibility, and population level estimates of hospitalization and ICU admission in pediatric populations have increased since Omicron became the predominant variant.3, 4

Throughout the pandemic, children have experienced social isolation, disruption to schooling and extra-curricular activities, which have had profound impacts on the mental and physical well-being of children and their families. These harms can disproportionately affect some children and families and may further exacerbate social inequities among some groups, including racialized and Indigenous communities, refugees and other newcomers to Canada, persons living in low-income settings, as well as children with disabilities.5 

In addition, broad vaccination for COVID-19 is a critical tool to best protect everyone, especially those at highest risk, from severe illness and death. While following current public health measures, individuals who are fully vaccinated can safely resume many activities that they did prior to the pandemic.
 

 

The latest information on the current state of COVID-19 in BC can be found on the COVID-19 Situation Report page including the rates COVID-19 infections in children. This page is updated monthly.

 

Clinical trial data indicate that the pediatric formulation of the Pfizer-BioNTech COVID-19 vaccine (10 mcg) produces a good immune response in children 5-11 years of age, similar to the response seen in young adults 16-25 years of age who received the adolescent/adult formulation (30 mcg). Preliminary efficacy of the 10 mcg dose of vaccine against symptomatic COVID-19 in children 5 to 11 years of age was estimated to be 90.7%. 


In clinical trials, the 50 mcg dose of Moderna vaccine produced a good immune response in children 6-11 years of age that was similar to the response produced in 18-25 year olds who received a 100 mcg dose of the vaccine. The preliminary efficacy of the 50 mcg dose of Moderna vaccine in children 6-11 years of age was 88% against confirmed symptomatic COVID-19 from 14 days after the first dose.


It is noted that vaccine effectiveness against SARS-CoV-2 infection has decreased since the Omicron variant became the predominant variant, however vaccine effectiveness against severe illness and hospitalization due to COVID-19 remains high. 

 

 

Dose escalation studies were conducted in phase 1 clinical trials to establish the appropriate dose on the basis of reactogenicity and immunogenicity of the administered doses. Based on these studies, a dose of 10 mcg was selected for the Pfizer-BioNTech pediatric vaccine6(one third of the adult/adolescent dose) while a dose of 50 mcg was selected for the Moderna vaccine (one half of the adult/ adolescent dose).6

 

 

No allergic events or anaphylactic reactions were reported after either dose. No serious adverse events (SAE) related to the vaccine, no cases of multisystem inflammatory syndrome in children (MIS-C), myocarditis/pericarditis or deaths were reported. Due to the size of the clinical trials, it is unlikely that any adverse events occurring at a frequency less often than 1 in 1,000 would be detected.

 

 
Phase 2/3 of clinical trial data evaluated the frequency of adverse events in children aged 5-11 years for the pediatric Pfizer-BioNTech vaccine  (10 mcg) and children 6-11 years for the Moderna vaccine (50 mcg). Local reactions including pain, redness and swelling were very common, appearing 1-2 days after any dose and typically resolved within 1-3 days. Systemic events were mild or moderate in severity and included fatigue, headache, muscle pain, chills, fever and joint pain. Onset of systemic events was within 1-4 days after vaccine receipt with a median duration of 1 day.
 

 

Refer to the COVID-19 mRNA Vaccine Comparison Table for the differences between the various formulations of the Pfizer-BioNTech COVID-19 vaccines. 

 
No cases of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the lining around the heart) were observed in the clinical trials of the COVID-19 mRNA vaccines in children 5-11 years of age. However, due to the number of study participants in the clinical trials, adverse events occurring at a frequency of less than 1 in 1,000 may not have been detected.

Cases of myocarditis and pericarditis  have been reported following vaccination with COVID-19 mRNA vaccines in Canada and internationally among individuals aged 12 years and older who received the 30 mcg formulation of the Pfizer-BioNTech COVID-19 vaccine or 100 mcg formulation of the Moderna COVID-19 vaccine; however, the risk is considered rare. 

Cases of myocarditis/pericarditis following COVID-19 mRNA vaccination occur most commonly in adolescents and young adults (12 to 30 years of age). It usually occurs within a week of vaccination and is more common:
  • After the second dose
  • In males than females
  • After receipt of the Moderna vaccine than the Pfizer-BioNTech vaccine.
The highest rate of myocarditis reported in Canada in association with the Pfizer COVID-19 mRNA vaccine has been for males aged 12 to 17 years following the 2nd dose, with about 7 cases per 100,000 doses. In both Canada and the US, no deaths attributed to the COVID-19 mRNA vaccine-related myocarditis have been identified in adolescents or young adults. 

Data from the US suggest the risk of myocarditis/pericarditis following mRNA COVID-19 vaccination may be higher in older adolescents aged 16-17 years compared to younger adolescents aged 12-15 years.7 In addition, surveillance data suggests that the risk of myocarditis/pericarditis within 7 days of receipt of the second dose of the pediatric Pfizer-BioNTech vaccine may be substantially lower in 5-11 year old males compared to adolescents who received the adult/adolescent Pfizer-BioNTech vaccine.8 

In US data reported to VAERS, the reported rates of myocarditis occurring within 7 days of vaccination among 5-11 year old males in association with the 2nd dose of Pfizer-BioNTech vaccine (10 mcg formulation) are one-eighteenth the rate reported in 12-15 year old males (30 mcg formulation) with a rate of 2.7 cases per million doses.

Symptoms of myocarditis/pericarditis can include shortness of breath, chest pain, or the feeling of a rapid or abnormal heart rhythm. Symptoms can be accompanied by abnormal test results (e.g., electrocardiogram, serum troponins, echocardiogram).9  Available data indicate that most individuals affected have responded well to conservative therapy and have recovered quickly.4

Based on the vaccine safety data for adolescents and adults, it is expected that longer intervals between doses of Pfizer-BioNTech vaccine will further reduce the very rare risk of myocarditis or pericarditis following vaccination in children 5-11 years of age.10  

Myocarditis following mRNA COVID-19 vaccination tends to have a similar epidemiologic profile to classic myocarditis (unrelated to COVID-19), as it occurs more commonly in adolescents and young adult males. Classic myocarditis is less common in younger children 5-11 years of age.6

A Children’s Hospital of Philadelphia article states, “This situation may cause some parents to consider taking a “wait and see” approach, delaying their child’s vaccination until more doses have been administered. However, what many parents don’t realize is that in teens and young adults — the group with the highest occurrence of this side effect — the risk of developing myocarditis is greater following natural infection.” The article included the following estimates for myocarditis following COVID-19 mRNA vaccination compared to myocarditis following COVID-19 infection:

Of 100,000 males aged 16 to 29 years of age, approximately 5 would develop myocarditis after COVID-19 mRNA vaccination and about 59 would develop myocarditis after COVID-19 infection.

If we consider 100,000 females aged 16 to 29, 1 would develop myocarditis after vaccination and about 39 would develop myocarditis after COVID-19 infection.

As such, the risk of experiencing myocarditis is greater in an unvaccinated person than a vaccinated person. Therefore, opting to delay or forgo vaccination to avoid myocarditis is opting to take the risk of developing COVID-19 infection, which could put the child at greater risk of experiencing myocarditis.11  
 

 
Yes. General immunization guidelines support the administration of a COVID-19 vaccine before, at the same visit, or after other vaccines at a different injection site(s) without regard to timing (this includes live and inactivated vaccines). If a client is due for more than one vaccine, providers are encouraged to offer all of the vaccines at the same visit. Concomitant administration of all recommended vaccines is important because it increases the probability that people will be fully vaccinated. It is also an important part of immunization practice if a healthcare provider is uncertain that a patient will return for additional doses of vaccine. This recommendation also aligns with the US CDC guidance.

Several recent studies evaluating the safety and immunogenicity of concomitant administration of COVID-19 vaccines with seasonal influenza vaccine in adults saw no safety concerns and antibody responses to both vaccines were maintained.12, 13, 14  To date, no safety concerns with concurrent vaccination of COVID-19 vaccines with other vaccines have been noted. Studies and surveillance activities to assess the safety and immunogenicity of concurrent administration of COVID-19 vaccines with other vaccines are ongoing.
 

 
 

‎Tromethamine (Tris or trometamol) is used as a buffer in vaccines and medications, including those for use in children, to improve stability and prevent pH fluctuations in the solution. Tromethamine is widely used in several medications for topical, enteral or parenteral administration. It is also used in cosmetics as an emulsifier.15 No safety concerns have been identified with tromethamine. While tromethamine has been identified as a potential allergen, a review of existing evidence did not identify any cases of allergic reactions to tromethamine in children.4 Tromethamine has been identified as a potentially allergenic excipient and is present in the pediatric Pfizer-BioNTech and Moderna COVID-19 vaccines. However, there is increasing evidence that tromethamine is not the culprit excipient and/or the reactions are not IgE-mediated. This remains under investigation.16 

 

Even though severe outcomes from COVID-19 in children are uncommon, they can occur.  Vaccinating children helps keep them safe, and helps them keep vulnerable people in their community such as; older adults, younger children and infants and people with other health conditions safe as well.


The following are additional key messages to share with parents about COVID-19 vaccination for children aged 5-11:

  • Without vaccination, all children will likely contract the virus at some point3
  • The benefits of vaccination will help protect their child from COVID-19 infection
  • Children who are infected with COVID-19 can develop multisystem inflammatory syndrome in children (MIS-C), a rare but serious condition. Although uncommon, as of July 23, 2022, there have been 32 cases of MIS-C in BC related to COVID-19 infection with a median age of 9 years (range  from 4 months to 16 years of age).
  • Their child's risk of severe outcomes from COVID-19 due to underlying medical conditions e.g., obesity, medically fragile/medical complexities, more than one underlying medical condition, neurological disorders, Down Syndrome and other immunocompromising conditions
  • Children who are infected with COVID-19 may also develop a post-COVID condition also known as long-COVID or post-acute COVID in which symptoms such as: brain fog/cognitive issues, breathlessness, fatigue, can continue for weeks or months. More information about Post-COVID-19 Care & Recovery can be found on the PHSA website.
  • Benefits of vaccination also include:
    • Reduced time away from school or activities, with positive impacts on physical and mental health of children as a whole 
    • Reduces their child's risk of becoming infected due to exposure to COVID-19 through in-person activities such as school, extra-curricular activities and in the community, realizing that this changes with time
  • The unknown risk of exposure to COVID-19 variants in the future should also be considered
  • Their child’s risk of transmitting COVID-19 to close contacts who themselves are at higher risk of severe outcomes due to older age or underlying medical conditions3
 

 
 

 
No. COVID-19 vaccines do not cause infertility and there is no scientific reason to believe that they will. Recent studies have shown that COVID-19 vaccines do not impact fertility.17, 18

The Society of Obstetricians and Gynaecologists of Canada (SOGC) addresses this online rumor in their recent statement stressing, “there is absolutely no evidence, and no theoretic reason to suspect that the COVID-19 vaccine could impair male or female fertility” and added, that “the widespread social media concern stems from misinformation about the similarities between syncytin-1 (used for placental implantation) and the SARS-CoV-2 spike protein. While the two proteins have several similar amino acids, they remain vastly different. The antibodies produced against the SARS-CoV-2 spike protein would not have cross-reactivity with syncitin-1.”19 
 

 

The dose of COVID-19 vaccine that a child receives is based on their age at presentation (see below).  An 11 year old child who received an age-appropriate dose of a COVID-19 mRNA vaccine who has turned 12 years of age when presenting for their second dose should receive the authorized dose for their age to complete their primary series. If the second dose is given as less than the authorized dose for the child's age the dose should still be consdered valid and the series complete. For more information refer to the Guidance Document on the Management of Inadvertent Vaccine Errors.


Note that the monovalent COVID-19 mRNA vaccine for 6 years of age and older is no longer supplied in Canada as of April 2023. 

 

 
1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Interim guidance on the use of bivalent Omicron-containing COVID-19 vaccines for primary series. 2023 Jun 9 [cited 2023 Jul 17]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-interim-guidance-use-bivalent-omicron-containing-covid-19-vaccines-primary-series/naci-statement-bivalent-primary-series.pdf.

2. BC Centre for Disease Control. COVID-19 situation report Week 29: July 17-July 23, 2022. Available from:  

3. National Advisory Committee on Immunization (NACI). July 2022. Recommendation on the use of Moderna Spikevax COVID-19 vaccine in children 6 months to 5 years of age. Available from:

https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-moderna-spikevax-covid-19-vaccine-children-6-months-5-years.html


4. Statement from the Council of Chief Medical Officers of Health (CCMOH): COVID-19 Vaccination in Children 5-11 years of age. Available from: https://www.canada.ca/en/public-health/news/2021/11/statement-from-the-council-of-chief-medical-officers-of-health-ccmoh-covid-19-vaccination-in-children-5-11-years-of-age.html

5. National Advisory Committee o Immunization (NACI). November 2021. Recommendation on the use of the Pfizer-BioNTech COVID-19 vaccine (10 mcg) in children 5-11 years of age. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines/pfizer-biontech-10-mcg-children-5-11-years-age.html

6. New England Journal of Medicine. (November 9, 2021). Evaluation of the BNT162b2 COVID-19 Vaccine in Children 5 to 11 Years of Age. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa2116298 

7. Oster, M. mRNA COVID-19 vaccine-associated myocarditis [slides presented at Advisory Committee on Immunization Practices (ACIP) meeting [Internet]. Atlanta (GA): Centers for Disease Control and Prevention (CDC); 2021 Nov 2 [cited 2021 Nov 10]. Available from: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-2-3/04-COVID-Oster508.pdf.

8. Su JR. COVID-19 vaccine safety updates: Primary series in children and adolescents ages 5-11 and 12-15 years and booster doses in adolescents 16-24 years [Internet]. Atlanta (GA): CDC COVID-19 Vaccine Task Force; 2022 Jan 5 [cited 2022 Mar 24]. Available from: 

9. Brighton Collaboration. Myocarditis/pericarditis case definition [Internet]. Decatur (GA): The Task Force for Global Health; 2021 Jul 16. Available from: https://brightoncollaboration.us/myocarditis-case-definition-update/ 

10. National Advisory Committee of Immunization (NACI). January 2022. NACI updated recommendations on the use of COVID-19 vaccine in children 5 to 11 years of age. Available from: 

11. Children’s Hospital of Philadelphia. (Nov. 11, 2021). Feature Article: 3 Considerations for COVID-19 Vaccination of 5-11 year old Children. Available from: https://www.chop.edu/news/feature-article-3-considerations-covid-19-vaccination-5-11-year-old-children 

12. Lazarus, R., Baos, S., Cappel-Porter, H., Carson-Stevens, A., et. al. (November 2021). Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. Available from: https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(21)02329-1.pdf 

13. Domnich A, Orsi A, Trombetta CS, Guarona G, Panatto D, Icardi G. COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy. Pharmaceuticals. 2022 Mar 8;15(3):322. Available at: https://doi.org/10.3390/ph15030322

14. Janssen C, Mosnier A, Gavazzi G, Combadière B, Crepey P, Gaillat J, Launay O, Botelho-Nevers E. Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. Human Vaccines & Immunotherapeutics. 2022 Oct 14:2131166. Available at: https://doi.org/10.1080/21645515.2022.2131166

15. Nilsson L, Csuth Á, Storsaeter J, Garvey LH, Jenmalm MC. Vaccine allergy: evidence to consider for COVID-19 vaccines. Curr Opin Allergy Clin Immunol. 2021 Aug 1;214:401,409. doi: 10.1097/ACI.0000000000000762.

16. Canadian Society of Allery and Clinical Immunology. (November 14, 2021). COVID-19 Vaccine Testing & Administration Guidance for Allergists/Immunologists from the CSACI. Available from: https://csaci.ca/wp-content/uploads/2021/11/2021-11-15-REVISED-UPDATE-COVID-19-Vaccine-Testing-Administration-Guidance_LBL.pdf

17. Bentov Y, Beharier O, Moav-Zafrir A, et al. Ovarian follicular function is not altered by sars-cov-2 infection or bnt162b2 mrna covid-19 vaccination. Hum Reprod. 2021. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34364311 

18. Wang M, Yang Q, Ren X, et al. Investigating the impact of asymptomatic or mild sarscov-2 infection on female fertility and in vitro fertilization outcomes: A retrospective cohort study. EClinicalMedicine. 2021;38:101013. Available at https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(21)00293-5/fulltext

19. Society of Obstetricians and Gynecologists of Canada. (March 2021). Statement on COVID-19 vaccination and fertility. Available from: https://sogc.org/common/Uploaded%20files/Latest%20News/EN_SOGCStatement_COVID-19Vaccination-Fertility.pdf 
 
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Booster dose for children 5-11 years

 
The risk of severe outcomes, including hospitalization, intensive-care unit (ICU) admission and death remains very low in children 5-11 years of age and evidence has shown that receiving a primary series of COVID-19 vaccines reduces the rate of hospitalization for children 5-11 years (0.5/100,000) compared to those who have been unvaccinated (0.9/100,000).1  However, in the context of heightened epidemiological risk and increased risk of severe illness for those with underlying medical conditions, booster doses are now being offered to children in this age group.

Children 5-11 years with an underlying medical condition that places them at high risk of severe illness due to COVID-19 should be offered a booster dose. This includes children who are moderately to severely immunocompromised and received a 3 dose primary series. An age-appropriate bivalent Omicron-containing mRNA vaccine is the recommended vaccine for the booster dose, and a Moderna bivalent product is preferred for those 6-11 years who are moderately to severely immunocompromised. 

All other children 5-11 years of age may be offered a booster dose. Similarly, a bivalent Omicron-containing mRNA vaccine is preferred for these individuals.2 In BC, the Pfizer-BioNTech BA.4/BA.5 
(10 mcg) vaccine is the preferred product for this group.

NACI is currently only recommending one booster dose after the primary series for individuals 5-11 years of age. However, at the provider’s discretion, a bivalent booster dose (as per recommended interval) could be offered to individuals considered at high risk of severe COVID-19 who have previously received a booster dose with the monovalent COVID-19 mRNA vaccine.2  For other individuals 5-11 years of age, the bivalent vaccine is not recommended if a monovalent booster has already been received, but may be provided upon parent/guardian request.  

For information on specific vaccine recommendation for children 5-11 years, see COVID-19 Vaccine Eligibility.

 

The booster dose should be offered at least 6 months after

completion of the primary series. A shorter interval of 5 months between the booster dose and the primary series may be warranted; however, a longer interval between vaccine doses may increase immune memory response which may be an important consideration for long-term immunity for children. 


Children who have had at least 2 doses of mRNA vaccine and have had a COVID-19 infection are well protected against serious disease and hospitalization; however, for those who wish to receive an additional dose, an interval of 6 months is recommended between vaccine or infection whichever was more recent.

 

‎There is currently no clinical evidence on the immunogenicity or efficacy of the Pfizer BA.4/5 Bivalent vaccine (10 mcg) in individuals 5-11 years of age. The regulatory review process leveraged preliminary clinical trial data on the Pfizer Bivalent BA.4/5 vaccine (30 mcg) in adolescents and adults ≥12 years of age, clinical trial data on the use of the Pfizer Bivalent BA.1 (30 mcg) and monovalent Omicron Pfizer BA.1 vaccines in adults, as well as immunogenicity and safety data of monovalent Pfizer-BioNTech Comirnaty (10 mcg) vaccine in individuals 5-11 years of age.2

 

 
Based on the safety cohort of 401 children 5 to <12 years of age in the clinical trial (C4591007) who received the monovalent booster (third dose), it was found that the booster dose was well tolerated in this age group. Most local and systemic adverse events following immunization (AEFI) were mild or moderate in severity. These included: pain, redness and swelling at the injection site, fatigue, headache, muscle pain, chills, joint pain, fever, diarrhea and vomiting. No serious adverse events related to the vaccine were reported  and there were no cases of MIS-C, myocarditis, pericarditis or death. Furthermore, no immediate adverse events (within 30 minutes) were reported following dose 3 of the monovalent Pfizer-BioNTech Comirnaty COVID-19 vaccine (10 mcg).1

When compared to dose 2, local reactions were reported at similar rates except for lymphadenopathy which was reported for 2.5% of those who received dose 3 compared to 0.9% following dose 2. Also, use of antipyretic and pain medications were slightly higher for dose 3 (30.7%) compared to dose 2 (21.8%). However, the rate of systemic reactions following dose 3  of the monovalent Pfizer-BioNTech Comirnaty COVID-19 vaccine (10 mcg) for children 5-11 years of age was lower than the rate of systemic reactions observed previously for adults ≥18 years of age following dose 3 of the monovalent Pfizer-BioNTech Comirnaty COVID-19 vaccine (30 mcg).1

For Pfizer-BioNTech BA.4/5 Bivalent vaccine (10 mcg), there is currently no safety data available in children 5 to 11 years of age. The regulatory review process leveraged preliminary clinical trial data on the Pfizer-BioNTech Bivalent BA.4/5 vaccine (30 mcg) in adolescents and adults ≥12 years of age, clinical trial data on the use of the Pfizer-BioNTech Bivalent BA.1 (30 mcg) and monovalent Pfizer-BioNTech Omicron BA.1 vaccines in adults, as well as immunogenicity and safety data of monovalent Pfizer-BioNTech Comirnaty vaccine (10 mcg) in individuals 5 to 11 years of age.2

 

1. National Advisory Committee of Immunization (NACI). August 2021. Recommendation on the use of a booster dose of Pfizer-BioNTech Comirnaty COVID-19 vaccine in children 5 to 11 years of age. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-first-booster-dose-pfizer-biontech-comirnaty-covid-19-vaccine-children-5-11-years.pdf


2. Public Health Agency of Canada [Internet] Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated recommendations on the use of COVID-19 vaccine booster doses in children 5 to 11 years of age and concurrent vaccine administration. 2022 Dec 9 [cited 2022 Dec 9]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/updated-recommendations-use-covid-19-vaccine-booster-doses-children-5-11-years-concurrent-administration.pdf


COVID-19 mRNA vaccines for children 6 months to 4 years

 

‎On July 14, 2022, Health Canada approved the Moderna COVID-19 mRNA vaccine (SPIKEVAXTM, 25 mcg dose) for use in children 6 months to 5 years of age.1


On September 9, 2022, Health Canada also approved the Pfizer-BioNTech COVID-19 mRNA vaccine (COMIRNATY®, 3 mcg dose) for children 6 months to 4 years of age.2

On June 9, 2023 NACI recommended the Moderna bivalent COVID-19 mRNA vaccine can be used for the  primary series in those 6 months to 4 years of age. NACI acknowledges that this recommendation is off-label and recommends that informed consent should include a discussion that this product has not yet been approved for use in the primary series or for use in those 6 months of age and older. 3

The primary series of Moderna Spikevax COVID-19 vaccine (monovalent and bivalent, 25 mcg) is a 2 dose series with an interval of at least 8 weeks between doses, whereas the Pfizer Comirnaty (3 mcg) COVID-19 vaccine is a 3 dose series with an interval of at least 8 weeks between each dose. In B.C, Moderna Spikevax (25 mcg) COVID-19 vaccines are the preferred product for this age group due to the additional dose required to complete the Pfizer Comirnaty (3 mcg) COVID-19 vaccine primary series and the extended time necessary to achieve optimal immunity.  Parents/guardians who wish to immunize their children with the Pfizer-BioNTech COVID-19 mRNA vaccine (COMIRNATY®, 3 mcg dose) should contact the call centre to request this vaccine, as it will not be routinely available at immunization clinics and is available by special request only.

Please refer to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 vaccines for complete information on the  COVID-19 vaccines prior to administration.

 

The minimum age for COVID-19 immunization is 6 months (not 24 weeks). For premature infants, chronological age based on actual birth date should be used as opposed to corrected age. 4

 

 
For children 6 months to 4 years of age who are moderately to severely immunocompromised, NACI recommends a primary series of three doses of Moderna  Spikevax (25 mcg) vaccine or Moderna Spikevax bivalent vaccine (0.1 mg/mL). NACI's recommendation for the use of Moderna Spikevax bivalent in the primary series or in those 6 months to 5 years of age is an off-label recommendation as this vaccine has not yet been approved by Health Canada for this use.  Informed consent should include a discussion that the bivalent COVID-19 mRNA vaccine has not yet been approved for use in the primary series or this age group. If either of the Moderna products are not available, a primary series of four doses of Pfizer-BioNTech Comirnaty (3 mcg) COVID-19 vaccine may be offered to ensure timely protection. Moderna Spikevax (25 mcg) is the preferred product for this population.2

Please refer to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 vaccines for complete information on the COVID-19 vaccines prior to administration.

 

NACI recommends that if readily available (i.e., easily available at the time of vaccination without delay or vaccine wastage), the same mRNA COVID-19 vaccine product should be offered for subsequent dose(s) in a vaccine series started with a specific mRNA COVID-19 vaccine. Therefore, if a child starts a series at 4 years of age with Moderna Spikevax (25 mcg) COVID-19 vaccine and turns 5 prior to completing their primary series, the Moderna Spikevax (25 mcg) COVID-19 vaccine is recommended to complete the series. However, when the same mRNA vaccine product is not readily available or is unknown, another COVID-19 mRNA vaccine product recommended in that age group (i.e., Pfizer Comirnaty vaccine [10 mcg]) can be considered  for completion of the series.1


‎NOTE: If any dose in the series is Pfizer-BioNTech COVID-19 vaccine (3 mcg), a total of 3 doses of vaccine should be administered. This includes children who start the series at 4 years of age and turn 5 prior to completing the series and for whom Pfizer-BioNTech 10 mcg dose is recommended. For those who are moderately to severely immunocompromised, if any dose in the series if Pfizer-BioNTech COVID-19 vaccine (3 mcg), a total of 4 doses of vaccine should be administered.

 

 
Yes. Co-administration of COVID-19 vaccines with other vaccines is in accordance with general best practices for immunization. To date, no safety concerns with concurrent vaccination of COVID-19 vaccines with other vaccines have been noted. Studies and surveillance activities to assess the safety and immunogenicity of concurrent administration of COVID-19 vaccines with other vaccines are ongoing.5
 
NACI recommends that for individuals 6 months of age and older, COVID-19 vaccines may be given concurrently, or anytime before or after, non-COVID-19 vaccines. This includes both live and non-live vaccines. This recommendation is based on the following observations: 1) no safety signals have emerged from ongoing post-market safety surveillance for mRNA COVID-19 vaccines in children 6 months to 5 years of age; and 2) there is no evidence of safety concerns of concurrent administration based on data from adults populations. In addition, concurrent administration will reduce barriers to the provision of routine childhood immunizations and seasonal influenza immunization.6  Experience with non-COVID 19 vaccines has shown immunogenicity and adverse event profiles are generally similar when vaccines are co-administered compared to when they are administered alone.7 Several recent studies evaluating the safety and immunogenicity of concomitant administration of COVID-19 vaccines with seasonal influeza vaccine in adults saw no safety concerns and antibody responses to both vaccines were maintained.8, 9, 10

Concomitant administration of vaccines is important as each client contact is an opportunity to review immunization status and administer all vaccines for which the client is eligible, increasing the probability that children will be fully vaccinated.2 Some children may be behind in their routine immunizations due to impacts of the pandemic, and concomitant administration allows for opportunistic catch-up of routine vaccines. This also mitigates the challenge for both healthcare providers and parents if multiple visits to healthcare providers are required to administer all recommended immunizations. If a child is due for more than one vaccine, providers are encouraged to offer all of the vaccines for which the child is eligible at the same visit to ensure they are up-to-date with vaccines based on their age and risk factors.
 

 
While the majority of children with COVID-19 have mild or asymptomatic disease, some children get severe disease and require hospitalization. Furthermore, children, adolescent and adults with SARS-CoV-2 infection are at risk of multisystem inflammatory syndrome (MIS) and post COVID-19 conditions (PCC). COVID-19 vaccination not only reduces the chance of infection, but evidence suggests that there is a lower risk of PCC amongst those who were vaccinated prior to their COVID-19 infection.5  

In the US, 9,499 MIS-C reports have been submitted to the CDC since mid-may 2020. Amongst these, 98% of the patients had a positive test result for SARS-CoV-2 and the remaining 2% had contact with someone with COVID-19. 14

Vaccination is an important tool and additional layer of protection for this age group to reduce the risk of severe illness.
 

 
It’s normal for parents/guardians to have questions about what is best for their children. Healthcare providers continue to be a trusted source for immunization information and as parents/guardians consider the possible risk and benefits of vaccinating their children, healthcare providers can be there to address their questions.

While the majority of children with COVID-19 have mild or asymptomatic disease, some children get severe disease and require hospitalization. Following infection with the SARS-CoV-2 virus children are also at risk of developing multisystem inflammatory syndrome in children (MIS-C) and may also develop a post-COVID condition also known as long-COVID or post-acute COVID. Unfortunately, we cannot predict which children could have severe outcomes associated with COVID-19 infection. 

Vaccinating their 6 month to 4 year old will provide their child with an additional layer of protection from COVID-19. Vaccinating their child may also help them to feel more comfortable when they are in group settings such as childcare and other activities.
 

 

‎Yes. Based on indirect evidence from adult populations, those who have been vaccinated against and infected with COVID-19 appear to develop stronger, more durable immunity compared to immunity developed from previous infections alone.1 If a child has already had COVID-19 infection, it is still recommended for them to receive a complete series of COVID-19 vaccine.


NACI’s earlier recommendations around intervals between previous infection and COVID-19 vaccination apply to this age group as well.1  Children 6 months to 5 years of age previously infected with SARS-CoV-2 can wait 8 weeks from infection (symptom onset or positive test if asymptomatic) to start or complete a COVID-19 primary vaccine series. For children who are considered moderately to severely immunocompromised a shorter interval of 4 to 8 weeks between SARS-CoV-2 infection and starting or completing a COVID-19 primary vaccine series may be considered.
 

 

‎Clinical trials took place while Omicron was the predominant variant of SARS-CoV-2 in the US and Canada. Vaccine efficacy among children aged 6 months to 5 years is primarily based on a comparison of immune responses in this age group to adults 18 to 25 years of age. The humoral immune response to Moderna Spikevax (25 mcg) COVID-19 vaccine was non-inferior in children aged 6 months to 5 years compared to young adults.1 


Vaccine efficacy was assessed among 5,476 participants who received two doses of either Moderna Spikevax (25 mcg) mRNA COVID-19 vaccine or placebo. 

For those without evidence of prior SARS-CoV-2 infection, efficacy against confirmed symptomatic SARS-CoV-2 infection starting 14 days after dose 2 was estimated at:
  • 50.6% among study participants aged 6 to 23 months 
  • 36.8% among participants aged 2 to 5 years
For those with or without evidence of prior SARS-CoV-2 infection, efficacy against confirmed symptomatic SARS-CoV-2 infection starting 14 days after dose 2 was estimated at:
  • 50.6% among study participants aged 6 to 23 months 
  • 36.5% among participants aged 2 to 5 years
During the Omicron wave, estimates of vaccine efficacy against symptomatic disease for Moderna Spikevax (25 mcg) COVID-19 vaccine in children 6 months to 5 years of age are similar with reported vaccine effectiveness for Pfizer-BioNTech Comirnaty (10 mcg) COVID-19 vaccine among children 5 to 11 years of age. 

The immunogenicity and safety of Moderna bivalent BA.1 as a primary series was evaluated in a phase 3 open-label study in 179 unvaccinated children 6 months to 5 years of age. In this study the antibody response 28 days after dose 2 for the BA.1 product was superior to that of the original Moderna vaccine.  This study also showed that local and systemic reactions after dose 1 and dose 2 of the bivalent vaccine were similar to the original Moderna vaccine. Although, Moderna Bivalent BA.1 COVID-19 vaccine is no longer available in Canada, these findings could be indirectly applied to Moderna BA.4/5 products.

In older age groups, real world evidence suggests mRNA vaccines have high vaccine effectiveness at preventing severe outcomes of COVID-19 including hospitalization and death. Within the adolescent populations mRNA vaccines have high vaccine effectiveness against hospitalization due to MIS-C.
 

 
The safety data for Moderna Spikevax (25 mcg) COVID-19 vaccine were obtained from the ongoing Phase2/3 clinical trials which included children 6 months to 5 years of age. The cut off for this analysis was on February 21, 2022 and at that time the study included 375 subjects 6 months to <1 year of age, 1,372 subjects who were 1 to <2 years of age and 3, 007 subjects who were 2 to <6 years of age. These subjects were followed up from 0 to 127 days after dose 1 and from 0-99 days after dose 2.

Overall, the safety analysis has indicated that the Moderna Spikevax (25 mcg) COVID-19 vaccine was well tolerated by children aged 6 months to 5 years and its safety and reactogenicity profile was consistent with Spikevax formulation for older age groups.1

The serious adverse events observed in the clinical trial included one participant in 6 months to <2 years age group who experienced grade 3 fever that occurred 6 hours after dose 1 which was followed by a febrile seizure. There was 1 event of anaphylaxis attributed to a concurrent medication in a 2-5 year old. There were two events of anaphylaxis deemed unrelated to vaccine in the under 2 age group.1

There were no deaths, no cases of MIS-C and no cases of myocarditis and/or pericarditis in any participant during the study period. However, since the clinical trial size was limited, it is unlikely to capture rare adverse events.1

There are post-market vaccine safety data available from the US for Moderna Spikevax (25 mcg) and Pfizer-BioNTech Comirnaty (3 mcg) vaccines. These data are from V-Safe, Vaccine Safety Datalink (VSD) and Vaccine Adverse Event Reporting System (VAERS) in the US which indicate COVID-19  mRNA vaccines are well tolerated among children aged 6 months to 5 years. No safety signals, including myocarditis, have been identified after administration of about 1.5 million vaccine doses.2 To access British Columbia’s monthly reports on adverse events following COVID-19 immunization, visit the BCCDC Vaccine Safety web page. 
 


 
 
In clinical trials, solicited adverse events were reported within 7 days following the receipt of either dose of vaccine. Common local and systemic adverse events according to age are as follows:
  • For children 6 months to 36 months of age: pain, redness, swelling, axillary (or groin) lymphadenopathy, fever, irritability/crying, sleepiness and loss of appetite 
  • For children 37 months to 5 years of age: pain, redness, swelling, axillary (or groin) lymphadenopathy, fever, headache, fatigue, myalgia, arthralgia, chills, nausea and vomiting.
Delayed injection site reactions, with onset on or after day 8 following vaccination, may occur in a small percentage of vaccine recipients, mostly after the first dose.‎

 
Vaccine efficacy of Pfizer-BioNTech Comirnaty (3 mcg) COVID-19 vaccines was assessed during the time when Omicron was the predominant circulating variant of SARS-CoV-2. Efficacy estimate data against confirmed COVID-19 from clinical trials are as follow:

Children 6 to 23 months:
  • At least 7 days after dose 3 with no prior infection: 73.2% estimated efficacy against confirmed symptomatic SARS-CoV-2 infection.
  • At least 7 days after dose 2 and before dose 3 with or without prior infection:  Observed vaccines efficacy was 15.6%. The estimated vaccine efficacy was 82.6% against Delta and 5.7% against Omicron variants.2 
Children 2 to 4 years:
  • At least 7 days after dose 3 with no prior infection: 71.8% estimated efficacy against confirmed symptomatic SARS-CoV-2 infection.
  • At least 7 days after dose 2 and before dose 3 with or without prior infection: Observed vaccine efficacy was 34.3%. The estimated vaccine efficacy was 56.0% against Delta and 31.2% against Omicron variants.2
Pfizer-BioNTech Comirnaty (3 mcg) was not evaluated for efficacy against severe COVID-19. In the clinical trials, 8 cases with severe outcomes were identified. Two of the cases had evidence of co-infection with other viruses. The remaining six were not considered as clinically significant by the  investigator. There were no deaths or cases of MIS-C among the trial participants. 

 
Overall, no safety signals were identified for Pfizer-BioNTech Comirnaty (3 mcg). The safety profile of the 3 mcg formulation was consistent with the known safety and reactogenicity profile of the 10 mcg and 30 mcg Pfizer-BioNTech Comirnaty formulations authorized for use in older age groups. Furthermore, the types of events reported in the vaccine group were consistent with events commonly reported for other pediatric vaccines authorized for use in children 6 months to 4 years of age. These reactions were moderate in severity with s median onset of 1-2 days and resolution within 1-2 days after onset.

There were no deaths, cases of myocarditis and/or pericarditis, MIS-C, Bell’s palsy or vaccine-related anaphylaxis reported during the study period. However, given that the trial was limited to 3,013 participants who were randomized to receive the vaccine, it is unlikely that rare or very rare AEs would be detected. NACI will monitor post-market safety surveillance data as it emerges and update its recommendations as needed.2

The safety data from the clinical trials are as follow:

Children 6 to 23 months:
  • Local reactions: These reactions were similar after dose 1 and dose 2 and slightly lower after dose 3. They were also less frequent than those seen for children 5 to 11 years of age who received Pfizer-BioNTech Cominraty (10 mcg).
  • Systemic reactions: These reactions were similar in frequency following dose 1, 2, or 3.
  • Serious adverse events (SAEs):  None of the events reported were considered to be related to the vaccines.2
Children 2 to 4 years:
  • Local reactions: Local reactions were similar in frequency after dose 1, 2 or 3. They were also less frequent than those seen for children 5 to 11 years of age who received Pfizer-BioNTech Cominraty (10 mcg).
  • Systemic reactions: Systemic reactions were similar after dose 1, 2 or 3. Systemic reactions such as fatigue, headache, chills and muscle pain were reported less frequently and were milder in severity compared to those seen for children 5-11 years of age. Fever was reported more frequently in this age group (4.9 to 5.3%) than in those 5 to 11 years of age (2.5 to 6.5%).
  • Serious adverse events (SAEs): Two events (fever and pain in the extremity) were reported by the same participant which were thought to be vaccine-related. This was a 4-year-old participant who fully recovered on day 10. A final diagnosis was not made despite the  investigations performed.2 
There are post-market vaccine safety data available from the US for Moderna Spikevax (25 mcg) and Pfizer-BioNTech Comirnaty (3 mcg) vaccines. These data are from V-Safe, Vaccine Safety Datalink (VSD) and Vaccine Adverse Event Reporting System (VAERS) in the US which indicate that COVID-19 mRNA vaccines are well tolerated among children aged 6 months to 5 years. No safety signals (including myocarditis) have been identified after administration of about 1.5 million vaccine doses.

To access British Columbia’s monthly reports on adverse events following COVID-19 immunization, visit the Vaccine Safety page on the BCCDC website. 

 

Tromethamine (Tris or trometamol) is used as a buffer in vaccines and medications, including those for use in children, to improve stability and prevent pH fluctuations in the solution. Tromethamine is widely used in several medications for topical, enteral or parenteral administration. It is also used in cosmetics as an emulsifier.13 No safety concerns have been identified with tromethamine. While tromethamine has been identified as a potential allergen, a review of existing evidence did not identify any cases of allergic reactions to tromethamine in children. 

Tromethamine has been identified as a potentially allergenic excipient and is present in the pediatric Pfizer-BioNTech and Moderna COVID-19 vaccines. However, there is increasing evidence that tromethamine is not the culprit excipient and/or the reactions are not IgE-mediated. This remains under investigation.17‎

 

 
No. COVID-19 vaccines do not cause infertility and there is no scientific reason to believe that they will. Recent studies have shown that COVID-19 vaccines do not impact fertility.18, 19  

The Society of Obstetricians and Gynaecologists of Canada (SOGC) addresses this online rumor in their recent statement stressing, “there is absolutely no evidence, and no theoretic reason to suspect that the COVID-19 vaccine could impair male or female fertility” and added, that “the widespread social media concern stems from misinformation about the similarities between syncytin-1 (used for placental implantation) and the SARS-CoV-2 spike protein. While the two proteins have several similar amino acids, they remain vastly different. The antibodies produced against the SARS-CoV-2 spike protein would not have cross-reactivity with syncitin-1.”20 
 

 
BCCDC provides information on COVID-19 vaccination for children and young people on Children and COVID-19 Vaccination  
page.

ImmunizeBC provides information for the public on COVID-19 vaccination for children age 6 months to 4 years in BC, including a Q&A for parents.

The Canadian Pediatric Society’s COVID-19 vaccine for children and youth Q&A offers information about COVID-19 vaccination in children including more information about vaccine safety in Canada. 

Children’s Hospital of Philadelphia’s website includes the resource Should my child get the COVID-19 vaccine? – a comprehensive Q&A for parents that helps to address misinformation and online rumours about COVID-19 vaccine (note this is a US based resource).
 

 

‎1. National Advisory Committee on Immunization (NACI). Recommendations on the use of Moderna Spikevax COVID-19 vaccine in children 6 months to 5 years of age. July 14 2022 [cited July 22, 2022]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-moderna-spikevax-covid-19-vaccine-children-6-months-5-years.pdf


2. National Advisory Committee on Immunization (NACI). Recommendations on the use of Pfizer-BioNTech Comirnaty (3 mcg) COVID-19 vaccine in children 6 months to 4 years of age. October 21, 2022 [cited October 26, 2022]. Available from https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-pfizer-biontech-comirnaty-3-mcg-covid-19-vaccine-children-6-months-4-years.pdf

3. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Interim guidance on the use of bivalent Omicron-containing COVID-19 vaccines for primary series. 2023 Jun 9 [cited 2023 Jul 17]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-interim-guidance-use-bivalent-omicron-containing-covid-19-vaccines-primary-series/naci-statement-bivalent-primary-series.pdf

4. BC Centre for Disease Control. BC Communicable Disease Control Manual, Chapter 2: Immunization, Part 1 - Immunization Schedules, p.3. October 2020 [cited July 22, 2022]. Available from: http://www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/Epid/CD%20Manual/Chapter%202%20-%20Imms/Part_1_Schedules.pdf

5. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide. COVID-19 vaccine. [updated 2023 Jul 13; cited 2022 Nov 18]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html

6. Public Health Agency of Canada [Internet] Ottawa (ON): Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated recommendations on the use of COVID-19 vaccine booster doses in children 5 to 11 years of age and concurrent vaccine administration. 2022 Dec 9 [cited 2022 Dec 9]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/updated-recommendations-use-covid-19-vaccine-booster-doses-children-5-11-years-concurrent-administration.pdf

7. Hall, E. Interim clinical considerations update for pediatric COVID-19 vaccines. US Center for Disease Control and Prevention. June 18, 2022 [cited July 22, 2022]. Available from: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-06-17-18/04-COVID-Hall-508.pdf

8. Lazarus, R., Baos, S., Cappel-Porter, H., Carson-Stevens, A., et. al. (November 2021). Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. Available from: https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(21)02329-1.pdf 

9. Domnich A, Orsi A, Trombetta CS, Guarona G, Panatto D, Icardi G. COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy. Pharmaceuticals. 2022 Mar 8;15(3):322. Available from: https://doi.org/10.3390/ph15030322

10. Janssen C, Mosnier A, Gavazzi G, Combadière B, Crepey P, Gaillat J, Launay O, Botelho-Nevers E. Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. Human Vaccines & Immunotherapeutics. 2022 Oct 14:2131166. Available from: https://doi.org/10.1080/21645515.2022.2131166

11. Centers for Disease Control and Prevention. COVID Data Tracker. Atlanta, GA: U.S. Department of Health and Human Services, CDC; 2023, July 17. https://covid.cdc.gov/covid-data-tracker

12. Nilsson L, Csuth Á, Storsaeter J, Garvey LH, Jenmalm MC. Vaccine allergy: evidence to consider for COVID-19 vaccines. Curr Opin Allergy Clin Immunol. 2021 Aug 1;214:401,409. doi: 10.1097/ACI.0000000000000762.

13. Canadian Society of Allery and Clinical Immunology. COVID-19 Vaccine Testing & Administration Guidance for Allergists/Immunologists from the CSACI. November 14, 2021 [cited July 25, 2022]. Available from: https://csaci.ca/wp-content/uploads/2021/11/2021-11-15-REVISED-UPDATE-COVID-19-Vaccine-Testing-Administration-Guidance_LBL.pdf

14. Bentov Y, Beharier O, Moav-Zafrir A, et al. Ovarian follicular function is not altered by SARS-CoV-2 infection or BNT162b2 mRNA covid-19 vaccination. Hum Reprod. 2021. Available from: https://www.ncbi.nlm.nih.gov/pubmed/34364311 

15. Wang M, Yang Q, Ren X, et al. Investigating the impact of asymptomatic or mild SARS-CoV-2 infection on female fertility and in vitro fertilization outcomes: A retrospective cohort study. EClinicalMedicine. 2021;38:101013. Available from: https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(21)00293-5/fulltext

16. Society of Obstetricians and Gynaecologists of Canada. Statement on COVID-19 vaccination and fertility. March 18, 2021. Available from: https://sogc.org/common/Uploaded%20files/Latest%20News/EN_SOGCStatement_COVID-19Vaccination-Fertility.pdf
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COVID-19 protein subunit vaccine (Novavax)

Refer to the BC Immunization Manual, Part 4 – Biological Products, COVID-19 vaccines for complete information on the COVID-19 protein subunit vaccine (Nuvaxovid™, Novavax) prior to administration.

 
While the National Advisory Committee on Immunization (NACI) continues to preferentially recommend the use of COVID-19 mRNA vaccines, they support the use of Novavax COVID-19 vaccine in Canada for those who have not yet received a primary series or booster dose and are not able (e.g., due to a contraindication or inaccessibility) or willing to receive an mRNA vaccine.

The authorization of the Novavax COVID-19 vaccine can help remove barriers to vaccination for people who want a protein-based vaccine or who are not willing or able to receive mRNA vaccines or viral vector vaccines. 

Having more authorized COVID-19 vaccines that meet Health Canada’s stringent safety, efficacy and quality requirements provides provinces and territories with an additional vaccine option to consider in their vaccination programs. In addition, Novavax COVID-19 vaccine storage and handling requirements are less complex than the COVID-19 mRNA vaccines as they are stored at refrigerator temperatures of +2°C to +8°C. 

 
The Novavax COVID-19 vaccine is a recombinant protein subunit vaccine. While this type of vaccine technology has been used for other vaccines such as the hepatitis B vaccine, this is the first COVID-19 vaccine authorized in Canada which uses this technology. 

Protein subunit vaccines are created by inserting a small piece of the virus’s genetic code into another cell (Novavax uses the Spodoptera frugiperda insect cell line) which instructs the cell to start building the virus spike protein from the original (Wuhan) strain. The virus spike protein is then extracted from the cell, purified and used as the active ingredient in the vaccine to stimulate an immune response. The Novavax COVID-19 vaccine includes a new type of adjuvant, Matrix-M, which helps the vaccine produce a better immune response.

 
The use of mRNA COVID-19 vaccines continues to be preferentially recommended due to the excellent protection they provide against severe illness and their well-known safety profile.
  
Individuals 12 years of age and older who are not able or not willing to receive a  COVID-19 mRNA vaccine, are eligible to receive Novavax COVID-19 vaccine for their primary series.  Individuals 18 years of age older are also eligible to receive Novavax COVID-19 vaccine as a booster dose if unable or unwilling to receive a COVID-19 mRNA vaccine.

 
The Novavax COVID-19 vaccine was evaluated in two pivotal Phase 3 trials: 2019nCoV-301 conducted in the United States and Mexico and 2019nCoV-302 conducted in the United Kingdom.1   

In clinical trial 2019nCoV-301, the estimated vaccine efficacy at least 7 days after Dose 2 was 90.4% (95% CI: 82.9 to 94.6%), with 14 confirmed COVID-19 cases identified among vaccine recipients (n=17,312) compared to 63 cases among placebo recipients (n=8,140). All cases identified in the vaccine group were mild.

In clinical trial 2019nCoV-302, the estimated vaccine efficacy after a median follow-up after Dose 2 of 54 and 56 days in the placebo and vaccine groups, respectively, was 89.7% (95% CI: 80.2 to 94.6%), with 10 confirmed COVID-19 cases among the vaccine recipients (n=7,020) compared to 96 cases in the placebo group (n=7,019).

The duration of protection is not yet known. There is currently no data on the efficacy or effectiveness of the vaccine against the Delta or Omicron variants as clinical trials were conducted before the emergence of those variants.1

 
Cellular immune responses specific to the SARS-CoV-2 spike protein were elicited 7 days after the first dose and increased 7 days after the second dose.1, 2 The Novavax COVID-19 vaccine induces both binding and neutralizing antibodies against the SARS-CoV-2 spike protein. While both the binding and neutralizing antibodies were seen after one dose, the maximal immune responses were seen 14 days after the second dose, on day 35. Antibodies were detectable up to day 189, with neutralizing antibodies declining more rapidly compared to binding antibodies.1

In clinical trials, binding and neutralizing antibody titres were slightly lower in older participants (≥65 years of age) compared to younger participants (18 to <65 years of age) after 2 doses.1
 

 
There is emerging evidence that longer intervals between the first and second doses of COVID-19 vaccines result in more robust and durable immune responses and higher vaccine effectiveness. 
Evidence on mRNA COVID-19 vaccines in adult populations indicates that a longer dose interval such as 8 weeks, compared with the authorized 21-day interval, improves the immune response and is associated with greater vaccine effectiveness that may last longer. A similar observation was also seen with longer intervals for the AstraZeneca COVID-19 vaccine. This is consistent with general principles of vaccinology, and expected to also apply to recombinant protein subunit COVID-19 vaccines.

Longer intervals between vaccine doses leading to better immune response is based on two immunological concepts: affinity maturation and decreased immune interference. With affinity maturation, more time between vaccine doses allows for optimal B cell maturation, so that when the immune system encounters the vaccine again it produces better binding antibodies that may be more robust and broad. These types of antibodies may result in better protection on exposure to the same or different variants of the virus.3  Immune interference may occur when a second dose of vaccine is introduced into the body when there is still a high level of circulating antibodies, these antibodies may mask binding sites on the vaccine antigen preventing a good response to the vaccine. Allowing time for circulating antibodies to decrease between doses will help prevent immune interference and optimize responses to vaccines.3
 

 

‎Although mRNA vaccines are the preferred COVID-19 vaccines due to the demonstrated high efficacy and effectiveness with longer term safety data, Novavax COVID-19 vaccine may be provided as a booster dose to individuals 18 years of age and older who are unable or unwilling to receive a COVID-19 mRNA vaccine, regardless of which COVID-19 vaccines were received in the primary series. 

 

 

Yes, Novavax COVID-19 vaccine may be used in a heterologous (mixed) primary series or as a booster dose in a heterologous prime-boost (booster dose differs from the COVID-19 vaccine product(s) used in the primary series) for whom mRNA COVID-19 vaccine is contraindicated, inaccessible or has been refused.  To complete their primary series, people may receive two doses of Novavax COVID-19 vaccine (homologous primary series) or one dose of Novavax COVID-19 vaccine and one dose of another COVID-19 vaccine (heterologous primary series).

 

 
Novavax COVID-19 vaccine is contraindicated for individuals with a history of anaphylactic reaction to a previous dose of the vaccine or to any component of the vaccine. These individuals should be offered an mRNA COVID-19 vaccine and observed for at least 30 minutes after immunization. 

The Novavax COVID-19 vaccine contains polysorbate 80 which is considered a potential allergen. Polysorbate 80 can be found in various products such as cosmetics and medical preparations including vitamin oils, tablets, and anticancer agents. 

For a complete list of components in the vaccine see page 5 of the Novavax Nuvaxovid™ Product Monograph.
 

 

In clinical trials, myocarditis was identified in two teenage males shortly after receiving a second dose of the Novavax COVID-19 vaccine resulting in a mild clinical course with complete resolution and no sequelae. The biological mechanisms of action that could explain the association of myocarditis and/or pericarditis occurring after receipt of a COVID-19 vaccine are still under investigation and the information currently available is insufficient to determine a causal relationship with the vaccine. Post-market safety surveillance is required to determine whether this is an adverse event of interest associated with Novavax COVID-19 vaccine.1 


Pericarditis and myocarditis in association with Novavax COVID-19 vaccine have been reported internationally and there has been 1 report in Canada (per Public Health Agency of Canada reports to May 26, 2023) meeting the Brighton Case Definition Levels 1-3.4,5  Data from Japan, Australia and Europe report approximately 0-4 cases of myocarditis and 13 cases of pericarditis per 100,000 doses administered, per the Canadian Immunization Guide. A longer interval of 8 weeks between primary series doses may reduce the likelihood of pericarditis and myocarditis, particularly for males 12-39 years of age.6  Most cases recover fully. The exact cause of these events is not known but is thought to be related to the immune response to the spike protein which is also important in immunity against COVID-19 virus.

Additional doses of a COVID-19 vaccine should be deferred in those who experienced a physician-diagnosed myocarditis or pericarditis event following a previous dose of a COVID19 vaccine. For guidance on how to proceed with further COVID-19 vaccination, see the PRECAUTIONS section of the COVID-19 product pages. Deferral is not required for those with a prior history of myocarditis or pericarditis that is unrelated to COVID-19 mRNA vaccines and are no longer being followed by a medical professional for heart issues.
 

 
Vaccine storage and handling information for Novavax COVID-19 vaccine can be found on product monograph for this vaccine.

More information on storage and handling requirements can be found in the BC Immunization Manual, Part 4 – COVID-19 Vaccines, NUVAXOVID™.

 
1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Summary of National Advisory Committee on Immunization (NACI) statement: Recommendations on the use of Novavax Nuvaxovid COVID-19 vaccine. 2022 Feb 17 [cited 2022 Mar 11]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-novavax-nuvaxovid-covid-19-vaccine.html 

2. Keech C, Albert G, Cho I, Robertson A, Reed P, Neal S, et al. Phase 1-2 Trial of a SARS-CoV-2 Recombinant Spike Protein Nanoparticle Vaccine. N Engl J Med. 2020 Dec 10;383(24):2320,2332. Available from: https://www.nejm.org/doi/10.1056/NEJMoa2026920 
 
3. Public Health Agency of Canada. Vaccine Confidence InfoBulletin. 2022 Jan. [cited 2022 Mar 15]. Issue 9.

4. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Reported side effects following COVID-19 vaccination in Canada. 2023 June 9 [cited 2023 August 10]. Available from: https://health-infobase.canada.ca/covid-19/vaccine-safety/

5. Sexson Tejtel SK, Munoz FM, Al-Ammouri I, Savorgnan F. Myocarditis and pericarditis: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data. Vaccine. 03/01/2022;40(10):1499-1511.  doi: 10.1016/j.vaccine.2021.11.074.

6. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide. COVID-19 vaccine. [updated 2023 Jul 13; cited 2023 Aug 10]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html
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Special considerations

 
The following are recommendations for COVID-19 immunization in some specific populations who were either excluded from, or were represented by small numbers of participants in clinical trials. The recommendations for these groups are evolving, and more data have become available in the future about both protection from the vaccine and its safety. 

More information on COVID-19 considerations in these populations can be found under clinically extremely vulnerable individuals on the COVID-19 vaccination toolkit for health professionals page.

Pregnant and lactating people 

Althought the safety and efficacy of the COVID-19 vaccines were not studied in people who are pregnant or breastfeeding in the clinical trials for these vaccines, evidence during the post-marketing period has evolved. Outcomes in participants who became pregnant during the clinical trials and fetal outcomes are reported through registries, and real-world evidence (mostly with mRNA vaccination) has become available. While a cautionary approach has been taken historically to immunization during pregnancy and lactation, accumulating data on safety of immunization with a variety of vaccines during pregnancy and breastfeeding over several decades has led to expanded recommendations for use of vaccines in pregnancy. Both NACI1 and the Society of Obstetricians and Gynaecologists of Canada (SOGC)2 have pre-existing general recommendations that inactivated viral vaccines can be safely given in pregnancy. The SOGC recommends that pregnant people, those contemplating pregnancy, and those who are breastfeeding who are at high risk of infection and/or morbidity from COVID-19 should be offered the vaccine.3 New data have become available from postmarketing surveillance without safety concerns being identified. This includes a recently published US study of 35,691 women who self-enrolled into a safety surveillance program and 221 women who reported adverse events through the passive surveillance system.4  

Both NACI and SOGC recommend that the pregnant or lactating person be informed about the evidence on the safety of mRNA COVID-19 vaccines in these populations. This information should include the findings that in some studies, pregnant individuals with COVID-19 infection are at higher risk of invasive ventilation compared to non-pregnant age-matched individuals. Severe morbidity in pregnancy is associated with similar risk factors to those seen in non-pregnant people, including older age, asthma, obesity, diabetes, hypertension and heart disease. Emerging evidence suggests that COVID-19 mRNA vaccination during pregnancy is immunogenic and results in comparable anntibody titres to those generated in non-pregnant women. Regarding theoretical risks of vaccine receipt, the COVID-19 vaccines are not live virus vaccines, and there is not a basis to consider that these would be harmful neither to the fetus nor to the breastfed infant. A small number of pregnant women were inadvertently enrolled in the phase 3 clinical trials and are being followed to the end of their pregnancy to assess outcomes. 


Immunocompromised 

Individuals who are immunosuppressed due to disease or treatment were not included in the initial COVID-19 vaccine clinical trials and as such there are limited data in these populations.5  Individuals who are immunosuppressed due to disease or treatment may have been observed to have a diminished immune response to the vaccine.

A primary series of three doses of an approved mRNA COVID-19 vaccine should be offered to individuals in the approved age group. For individuals who previously received a 1- or 2-dose complete COVID-19 series, an additional dose should be offered.

People living with stable HIV that are considered immunocompetent may receive the COVID-19 vaccine.5

Autoimmune disorders

Although participants with autoimmune conditions who were not immunosuppressed were not excluded from clinical trials of the vaccines, these constituted a very small proportion of trial participants and represent a very narrow range of autoimmune conditions. Specific conclusions about efficacy and safety, including risk of exacerbation of the condition, were not assessed. This theoretical risk of exacerbation was based on previous studies of mRNA vaccines designed for treatment of cancer and ability of the mRNA vaccines to elicit inflammation. The current mRNA COVID-19 vaccines have been optimized to reduce this risk.5

The Canadian Rheumatology Association recommends that on balance, a complete COVID-19 vaccine series should be offered to individuals otherwise eligible to receive the vaccine without additional barriers such as an individualized risk assessment or documented approval to proceed with immunization from their health care provider, with the exception of individuals on treatment with rituximab. Treatment with rituximab is expected to decrease effectiveness of the vaccine because of B-cell suppression. Such individuals should be off treatment for 5 months or longer prior to vaccination, and after vaccination, should not restart rituximab for at least 4 weeks in order to allow for adequate response to the vaccine. While other drug therapies for autoimmune disorders may reduce the immune response to the vaccine, most recipients will derive benefit from vaccination.6  

Individuals with autoimmune rheumatic diseases presenting for COVID-19 immunization who wish to proceed with vaccination, other than those treated with rituximab, should be offered immunization without referral to their health care provider. Those who are uncertain and wish to seek further advice can be referred to a decision aid developed by the Canadian Rheumatology Association with input from the Canadian Arthritis Patient Alliance. Alternately, they may prefer to have this discussion with their health care provider most familiar with their disease and treatment. 

 

NACI continues to recommend that COVID-19 vaccines should be offered to people who have previously been infected with SARS-CoV-2.  While COVID-19 vaccine can be offered to individuals at any time following recovery from SARS-CoV-2 infection without contraindication, individuals who have had at least 2 doses of mRNA vaccine and have had a COVID-19 infection are well protected against serious disease and hospitalization. However, for those who wish to receive an additional dose of vaccine, an interval of 6 months is recommended between vaccine or infection whichever was more recent. This recommendation is based on the emerging evidence on hybrid immunity and the superior protection it provides against COVID-19. NACI has developed interim guidance based on immunological principles, expert opinion and available evidence related to vaccine safety, immunogenicity, and vaccine effectiveness. Therefore, with the goal of improving long-term protection, NACI recommends that:

  • Individuals under 5 years of age who have a recent positive COVID-19 test result (PCR or rapid antigen test) before starting or completing their primary COVID-19 vaccine series may receive the vaccine 8 weeks after symptoms started or after testing positive (if no symptoms were experienced).
  • Individuals who are recommended to receive a booster dose that have a recent positive COVID-19 test result (PCR or rapid antigen test or a history of having symptoms of COVID-19 while a household contact of someone who tested positive for COVID-19) may receive a booster dose at an interval of 6 months from the last dose of vaccine or infection whichever was more recent.  For more information see Booster doses section.
The longer intervals between infection and vaccination, as noted above, may result in a better immune response and longer-lasting protection against Omicron and future variants, and the likelihood of reinfection during these periods of time is small. However, risk factors for exposure and severe outcomes should be assessed when considering longer intervals. Individuals who wish to be vaccinated sooner can receive an initial or subsequent dose of COVID-19 vaccine following SARS-CoV-2 infection as soon as their symptoms have resolved and they are no longer required to self-isolate. 

 

Yes. General immunization guidelines support co-administration of other indicated vaccines at the same visit, at a different injection site(s). This includes both inactivated and live vaccines. If not given at the same visit, these vaccines can be given any time before or after the COVID-19 vaccine.


Co-administration of COVID-19 vaccines with other vaccines is in accordance with general best practices for immunization, and is supported by the US Center for Disease Control and Prevention and the World Health Organization. 

Data from recent studies also support the co-administration of COVID-19 and influenza vaccines.  These studies have found co-administration to be safe and the immune response towards all influenza strains and the SARS-CoV-2 spike protein with co-administration is generally non-inferior to that seen when either vaccine is administered alone.7-13 There are also data to support the co-administration of COVID-19 vaccine and pneumococcal polysaccharide 23 vaccine.7  The overall rate of solicited local and systemic adverse events was similar between subjects who received COVID-19 and influenza vaccine and those who received the COVID-19 vaccine alone. The adverse events reported were mostly mild-to-moderate and self-limiting.13 

Co-administration recommendations have been provided by Public Health in other countries, including Italy, France, Germany, Spain, Finland, the UK, Russia, and Australia.13  Co-administration has several potential benefits, including improved patient convenience and compliance, simplified immunization schedules, fewer missed opportunities to vaccinate, reduced costs, and logistical 
advantages. 13

 
Currently all COVID-19 vaccines approved for use in Canada are inactivated vaccines (not live vaccines) and antivirals have no effect on the response to inactivated vaccines. Therefore, clients receiving COVID-19 antiviral treatment can safely receive the COVID-19 vaccine. However, if the client is still experiencing symptoms of the viral illness for which the medication was prescribed, it might be best to delay the immunization so that the cause of any additional or worsening symptoms can easily be determined. 

For additional information, see the BC Immunization Manual, Appendix C - Contraindications and Precautions for Immunization

 
There are currently no data to inform whether COVID-19 vaccines affect TST or IGRA results. However, current knowledge about the immunologic response to COVID-19 vaccination is that it does not appear to impact TST or IGRA results. At the outset of the COVID-19 vaccination programs, there was a theoretical concern that COVID-19 vaccines may temporarily affect cell-mediated immunity, resulting in false-negative TST or IGRA test results.14

However, in cases where an opportunity to perform the TST or IGRA test might be missed, the testing should not be delayed since these are theoretical considerations. Therefore, TST and IGRA tests can be administered and read without regard to COVID-19 immunization. Re-testing (at least 4 weeks post immunization) of individuals with negative results for whom there is high suspicion of TB infection may be prudent in order to avoid missing cases due to potentially false-negative results.14, 15

 
If administration of the second dose of a COVID-19 vaccine is delayed, the second dose should be provided as soon as possible, and the series does not need to be restarted. In general, regardless of the time between doses, interruption of a vaccine series does not require restarting the series as delays between doses do not result in a reduction in final antibody concentrations for most other vaccines requiring more than one dose for a series. Maximum protection may not be attained until the complete vaccine series has been administered.

In BC, while vaccine supplies were limited, the time between first and second dose was extended to up to 4 months. This allowed a greater number of people to receive the important protection from a first dose of vaccine, given limited vaccine supply currently and high rates of COVID-19 transmission. The Canadian National Advisory Committee on Immunization (NACI) supported the delay of the second dose up to 4 months.16  

As of May 27, 2021, the recommended interval between dose 1 and 2 for the mRNA vaccines (Pfizer-BioNTech or Moderna) is 8 weeks. The recommended interval between dose 1 and 2 of the viral vector-based vaccines (AstraZeneca or COVISHIELD) is 8 to 12 weeks. Note that the AstraZeneca and COVISHIELD vaccines are no longer available for use in Canada.

More information on the evidence and the decision to defer the second dose of COVID-19 vaccine in BC can be found in the Public health statement on deferral of second dose COVID-19 vaccine in BC.

 

Prophylactic oral analgesics or antipyretics (e.g., acetaminophen or non-steroidal anti-inflammatory drugs such as ibuprofen) should not be routinely used before or at the time of vaccination. While these medications may be used after vaccination (see below), it is not known whether these may blunt the antibody response to vaccine. This phenomenon has been observed in some studies of other vaccines in children, although its clinical significance is unknown.17-19 If an individual has taken one of these medications prior to immunization for any reason, they should be immunized as planned.  

 

Oral analgesics or antipyretics may be considered for the management of symptoms attributed to the vaccine (e.g., pain, fever, headache, myalgia) if these cannot be readily tolerated using non-pharmaceutical strategies.   

 

 
Lymphadenopathy (reactive adenopathy related to the immune response generated by the vaccine) in the regional nodes draining the deltoid area can occur. Such enlarged nodes may be viewed in imaging studies such as mammograms, and may be interpreted as abnormal and indicative of potential pathology. 

The BC Cancer Agency recommends that scheduled screening mammograms should not be cancelled or delayed because of COVID-19 immunization. Those undertaking imaging within 6 weeks following vaccination should be asked for information about the site of vaccination so that this information can be recorded and considered in the interpretation of the radiograph.20

For those being vaccinated in the context of suspect or known breast malignancy, the vaccine should be given in the contralateral arm for both doses.  

 
There have been increasing reports that some clients are requesting injection with aspiration. These requests are likely due to two recent studies in mice that seem to establish the possible link between small chances of vaccine leakage into the bloodstream and either rare instances of myocarditis or thrombosis with thrombocytopenia syndrome (TTS).21, 22     

As indicated in the BC Immunization Manual, Appendix B: Administration of Biological Products, aspiration prior to injection of a vaccine is no longer recommended as there are no large blood vessels at the recommended immunization sites and aspiration can increase pain resulting from the combined effects of a longer needle-dwelling time in the tissues and shearing action (wiggling) of the needle.23, 24 Aspiration was originally recommended for theoretical safety reasons, however the veins and arteries within reach of a needle in the anatomic areas recommended for vaccination are too small to allow an intravenous push of vaccine without blowing out the vessel.24

While there is no evidence to support the need for aspiration, there is no prohibition on aspiration when administering a vaccine. Therefore, to avoid barriers and missed opportunities for COVID-19 immunization, this procedure could be done to accommodate case-by-case requests. However, clients should be informed of the possibility of increased pain and discomfort at the injection site. Providing the rationale for not aspirating with injection may assist the client in making an informed choice on the procedure which may include the following information: 
  • There is no scientific evidence to support the need for aspiration 
  • There are no published reports of adverse effects associated with not aspirating 
  • The deltoid site used for intramuscular injection is not in close proximity to large blood vessels, therefore the possibility of inadvertently hitting a blood vessel is rare
  • For aspiration to be effective, it must be sustained for at least 5-10 seconds 
  • Injection with aspiration is more painful, likely because aspiration, when performed correctly for 5-10 seconds, results in longer contact time between the needle and the tissue and movement of the needle within the tissue during aspiration is expected
  • Bleeding at the injection site is common, and does not indicate incorrect injection technique or injection into a blood vessel
 

 
Needle aspiration is performed by pulling back on the plunger (applying negative pressure) of the syringe after inserting the needle into the client and prior to injecting the vaccine and includes the following steps:
  • After the needle pierces the skin, use the thumb and forefinger of the non-dominant hand to hold the syringe barrel
  • Move the dominant hand to the end of the plunger 
  • Avoid moving the syringe 
  • Aspirate by holding the barrel of the syringe steady with your non dominant hand and by pulling back on the plunger with your dominant hand25 
Effective aspiration may require 5 to 10 seconds prior to injection; if blood appears in the barrel of the syringe during this time, do not inject the vaccine and withdraw the needle, and properly discard the syringe.26 


 

1. National Advisory Committee on Immunization. Canadian Immunization Guide [Internet]. Evergreen ed. Ottawa (ON): Public Health Agency of Canada; 2012 [updated 2020 Dec 24]. Part 3 - Immunization in pregnancy and breastfeeding; [cited 2021 Jan10]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-3-vaccination-specific-populations/page-4-immunization-pregnancy-breastfeeding.html

 

2. The Society of Obstetricians and Gynaecologists of Canada [Internet]. Ottawa (ON): The Society of Obstetricians and Gynaecologists of Canada. SOGC statement on COVID-19 vaccination in pregnancy. 2021 Jan 11 [cited 2021 Jan 13]. Available from: https://sogc.org/common/Uploaded%20files/Covid%20Information/SOGC_Statement_COVID-19_Vaccination_in_Pregnancy.pdf

 

3. Castillo E and Poliquin V. Immunization in pregnancy. J Obstet Gynaecol Can [Internet]. 2018 Apr [cited 2021 Jan 10];40(4):478-89. Available from: 

https://www.jogc.com/pb/assets/raw/Health%20Advance/journals/jogc/JOGC-672.pdf

 

4. Shimabukuro TT, Kim SY, Myers TR, Moro PL, Oduyebo T, Panagiotakopoulos L, Marquez PL, Olson CK, Liu R, Chang KT, Ellington SR, Burkel VK, Smoots AN, Green CJ, Licata C, Zhang BC, Alimchandani M, Mba-Jonas A, Martin SW, Gee JM, Meaney-Delman DM; CDC v-safe COVID-19 Pregnancy Registry Team. Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons. N Engl J Med. 2021 Apr 21. doi: 10.1056/NEJMoa2104983. Epub ahead of print. PMID: 33882218.

5. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. 2021 April 23 [cited 2021 April 28]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci.html


6. Canadian Rheumatology Association. Recommendations on COVID-19 vaccination in persons with autoimmune rheumatic disease. January 2021. https://rheum.ca/wp-content/uploads/2021/11/V3_Nov_23_2021_EN.pdf

 

7. Chen H, Huang Z, Chang S, Hu M, Lu Q, Zhang Y, Wang H, Xiao Y, Ge Y, Zou Y, Cui F. Immunogenicity and safety of an inactivated SARS-CoV-2 vaccine (Sinopharm BBIBP-CorV) coadministered with quadrivalent split-virion inactivated influenza vaccine and 23-valent pneumococcal polysaccharide vaccine in China: A multicentre, non-inferiority, open-label, randomised, controlled, phase 4 trial. Vaccine. 2022 Aug 26;40(36):5322-32. Available from: https://doi.org/10.1016/j.vaccine.2022.07.033  


8. Izikson R, Brune D, Bolduc JS, Bourron P, Fournier M, Moore TM, Pandey A, Perez L, Sater N, Shrestha A, Wague S. Safety and immunogenicity of a high-dose quadrivalent influenza vaccine administered concomitantly with a third dose of the mRNA-1273 SARS-CoV-2 vaccine in adults aged≥ 65 years: a phase 2, randomised, open-label study. The Lancet Respiratory Medicine. 2022 Apr 1;10(4):392-402. Available from: https://doi.org/10.1016/S2213-2600(21)00557-9


9. Lazarus R, Baos S, Cappel-Porter H, Carson-Stevens A, Clout M, Culliford L, Emmett SR, Garstang J, Gbadamoshi L, Hallis B, Harris RA. Safety and immunogenicity of concomitant administration of COVID-19 vaccines (ChAdOx1 or BNT162b2) with seasonal influenza vaccines in adults in the UK (ComFluCOV): a multicentre, randomised, controlled, phase 4 trial. The Lancet. 2021 Dec 18;398(10318):2277-87. Available from: https://doi.org/10.1016/S0140-6736(21)02329-1


10. Toback S, Galiza E, Cosgrove C, Galloway J, Goodman AL, Swift PA, Rajaram S, Graves-Jones A, Edelman J, Burns F, Minassian AM. Safety, immunogenicity, and efficacy of a COVID-19 vaccine (NVX-CoV2373) co-administered with seasonal influenza vaccines: an exploratory substudy of a randomised, observer-blinded, placebo-controlled, phase 3 trial. The Lancet Respiratory Medicine. 2022 Feb 1;10(2):167-79. Available from: https://doi.org/10.1016/S2213-2600(21)00409-4 


11. Janssen C, Mosnier A, Gavazzi G, Combadière B, Crepey P, Gaillat J, Launay O, Botelho-Nevers E. Coadministration of seasonal influenza and COVID-19 vaccines: A systematic review of clinical studies. Human Vaccines & Immunotherapeutics. 2022 Oct 14:2131166. Available from: https://doi.org/10.1080/21645515.2022.2131166


12. Shenyu W, Xiaoqian D, Bo C, Xuan D, Zeng W, Hangjie Z, Qianhui Z, Zhenzhen L, Chuanfu Y, Juan Y, Gang Z. Immunogenicity and safety of a SARS-CoV-2 inactivated vaccine (CoronaVac) co-administered with an inactivated quadrivalent influenza vaccine: A randomized, open-label, controlled study in healthy adults aged 18 to 59 years in China. Vaccine. 2022 Aug 26;40(36):5356-65. Available from: https://doi.org/10.1016/j.vaccine.2022.07.021


13. Domnich A, Orsi A, Trombetta CS, Guarona G, Panatto D, Icardi G. COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy. Pharmaceuticals. 2022 Mar 8;15(3):322. Available from: https://doi.org/10.3390/ph15030322


14. Centers for Disease Control and Prevention [Internet]. Atlanta (GA): U.S. Department of Health & Human Services.  Interim clinical considerations for use of mRNA COVID-19 vaccines currently authorized in the United States; [updated 2021 Jan 6; cited 2021 Jan 8]. Available from:  https://www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html

 

15. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Summary of updates in the Canadian Immunization guide of August 29, 2022: Updated guidance on COVID-19 vaccines in Canada. 2022 Aug 29 [cited 2022 Aug 29]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/summary-updates-canadian-immunization-guide-august-29-2022-covid-19-vaccines.html


16. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. NACI rapid response: Extended dose intervals for COVID-19 vaccines to optimize early vaccine rollout and population protection in Canada. 2021 Mar 8 [cited 2021 Mar 16]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/rapid-response-extended-dose-intervals-covid-19-vaccines-early-rollout-population-protection.html

 

17. Saleh E, Moody MA, Walter EB. Effect of antipyretic analgesics on immune responses to vaccination. Hum Vaccin Immunother [internet]. 2016 Sep 1 [cited 2021 Jan 10];12(9):2391-402. Available from: https://www-tandfonline-com.ezproxy.library.ubc.ca/doi/full/10.1080/21645515.2016.1183077 

 

18. Chau-Giendinning H, Baber B, Neher JO, Safranek S. Do prophylactic antipyretics reduce vaccination-associcated symptoms in children? J Fam Pract [Internet]. 2020 Apr [cited 2021 Jan 10];69(3):E21-22. Available from: https://cdn.mdedge.com/files/s3fs-public/JFP06904e21.pdf

 

19. Das RR, Panigrahi I, Naik SS. The effect of prophylactic antipyretic administration on post-vaccination adverse reactions and antibody response in children: a systematic review. PLoS One [Internet]. 2014 Sep 2 [cited 2021 Jan 10];9(9):e106629. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106629

 

20. BC Cancer. COVID-19 and Cancer Screening. Does the COVID-19 vaccine affect my screening mammogram? Accessed April 28, 2021. http://www.bccancer.bc.ca/screening/health-professionals/covid-19-and-cancer-screening


21. Li C., Chen Y., Zhao, Y., et al. Intravenous injection of COVID-19 mRNA vaccine can induce acute myopericarditis in mouse model. Clin Infect Dis. 2021 Aug 18: ciab707. doi: 10.1093/cid/ciab707. Epub ahead of print. PMID: 34406358; PMCID: PMC8436386. Available from: https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab707/6353927 
 
22. Nicolai L, Leunig A, Pekayvaz K, et al. Thrombocytopenia and splenic platelet directed immune responses after intravenous ChAdOx1 nCov-19 administration. bioRxiv [Preprint]. June 29, 2021. doi:10.1101/2021.06.29.450356. Available from: https://www.biorxiv.org/content/10.1101/2021.06.29.450356v1.full.pdf 

23. National Advisory Committee on Immunization. Canadian Immunization Guide [Internet]. Evergreen ed. Ottawa (ON): Public Health Agency of Canada; 2012 [updated 2017 Nov 3]. Part 1 - Key Immunization Information: Vaccine Administration Practices; Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-8-vaccine-administration-practices.html

24. CDC. Epidemiology and Prevention of Vaccine-Preventable Diseases. The Pink Book Course TextBook 14th edition. Chapter 6: Vaccine Administration. Available from: https://www.cdc.gov/vaccines/pubs/pinkbook/vac-admin.html

25. Clinical Skills [Internet]. Maryland Heights (MO): Elsevier Inc. 2021. Skills: Medication Administration: Intramuscular Injection; Available from: https://point-of-care.elsevierperformancemanager.com/skills/376/quick-sheet?skillId=GN_21_5  

26. Moshe Ipp, Anna Taddio, Jonathan Sam, Morton Goldbach, and Patricia C Parkin. (2007). Vaccine‐related pain: randomised controlled trial of two injection techniques. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2066084/

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Individuals who are immunocompromised

 
NACI strongly recommends that moderately to severely immunocompromised individuals in the authorized age group be vaccinated as follows:

Those who have not received a complete COVID-19 vaccine series:
  • Should be immunized with a primary series of three doses of mRNA vaccine.1
  • For individuals 6 months and older who are immunocompromised, Moderna Spikevax monovalent or  bivalent vaccines are the preferred product for primary series* and booster doses.
*This is based on NACI's recommendation on off-label use of bivalent COVID-19 mRNA vaccines. Informed consent should include a discussion that this vaccine has not yet been approved for use in the primary series or for use in those 6 months to 5 years of age. Furthermore, if unavailable, or upon client request, an age-appropriate Pfizer COVID-19 mRNA vaccine can be given.

Those who previously received a complete primary COVID-19 vaccine series (including one dose of Janssen vaccine, or a mixed series of mRNA/viral vector vaccines):
  • Should receive a booster dose of mRNA vaccine. 
 

 
To date, people with moderately to severely compromised immune systems have been observed to generally have lower antibody responses and lower vaccine effectiveness from a complete 2-dose vaccine series (1-dose if vaccinated with Janssen vaccine) than immunocompetent individuals, although this varies depending on the underlying condition or immunosuppressive agents. 

Although the evidence is limited, observational studies show a reduction in vaccine effectiveness against SARS-CoV-2 infection and disease in immunocompromised adults when compared to the general population. A pooled analysis of three large population-based cohort studies 2, 3, 4 estimated vaccine effectiveness against any SARS-CoV-2 infection after the second dose in immunocompromised persons to be 79% (95% confidence interval (CI): 69-91%), compared to vaccine effectiveness after the second dose in the general population of 90% (95% CI: 86-95%).

The impact of immunocompromise on seroconversion after vaccination varies according to specific conditions and/or immunosuppressive therapy. Not all immunocompromised populations have been studied in detail. 

In addition, breakthrough infections (infection in fully vaccinated people) have occurred. This may be due to some degree of evasion of vaccine-induced immunity or waning of vaccine-induced immunity over time, or poor immune response to initial vaccine doses (as might occur amongst those who are moderately or severely immunocompromised). In order to reduce the risk of breakthrough infections among vulnerable groups several countries including Israel, the United States, France, Germany, the United Kingdom, Denmark and Norway have implemented, or are planning to implement, the administration of third doses of COVID-19 vaccine in some immunocompromised populations.
 

 

The additional dose of COVID-19 vaccine should be provided at least 28 days after the completion of the 2-dose series (1-dose if vaccinated with Janssen vaccine). Although studies on immunogenicity have shown that an interval longer than the minimum 28 days between doses is likely to result in a better immune response, use of an interval longer than 28 days should be considered against the risk of exposure to SARS-CoV-2 due to current epidemiology, variants of concern and the risk for severe disease. Some immunocompromised individuals may still be susceptible after the 2-dose primary series, so their period of susceptibility until receipt of the additional dose will also increase if the interval between doses is increased.

 
The clinically extremely vulnerable (CEV) originally prioritized for COVID-19 vaccination included those people who would be more at risk of serious illness or hospitalization if they got COVID-19. However, many of the people in this group do mount a good immune response to the vaccine and are protected. 

Data now supports that a group of severely immunocompromised people whose immune response to a two-dose series is likely to be blunted, or not respond at all, should be offered a third dose to increase their chances of having a protective immune response with their initial vaccine series. 

Within the CEV group, there are people whose conditions made them at risk of serious illness if they got COVID-19 but whose condition does not prevent them from getting good protection through a good immune response from the two vaccine doses. People with these conditions do not require an additional dose. The evidence of vaccine effectiveness is reviewed closely for all CEV subgroups and the general population. If the evidence changes over time that will be considered in B.C.’s provincial vaccine strategy moving forward. 
 

 

Since the appearance of the Omicron variant, infection rates have markedly increased among Canadian children reaching record-high levels since the start of the pandemic.6 Although the risk of severe outcomes remains low for this age group, children with immunocompromising conditions are at increased risk.6 B.C. guidelines have aligned with NACI and recommend that children 6 months of age and older with the eligible conditions that make them moderately to severely immunocompromised receive a third dose of vaccine for their primary series.7 NACI recommends that children 5 to 11 years of age who are moderately to severely immunocompromised receive three doses of a COVID-19 mRNA vaccine authorized for their age. For children 6 months to 5 years of age, NACI recommends a primary series of three doses of Moderna SpikevaxTM (25 mcg) vaccine. For additional details on products recommended for each age group in B.C., refer to the COVID-19 Vaccine Eligibility.

 

 
In ten studies in adults, (five in solid organ transplant patients, three in patients on dialysis, one in patients with non-hematologic cancer and one in patients with hematologic cancer), the reactogenicity of a third dose of COVID-19 vaccine was similar to that of prior doses. In nearly all studies, the third dose was an mRNA vaccine, with the exception of one study where Janssen was also used for some study participations as an additional dose following a 2-dose mRNA COVID-19 vaccine primary series. However, there are no data specific to the Janssen COVID-19 vaccine when used as an additional dose in this population. No worsening of underlying disease was reported after immunization, however a few cases of graft versus host disease or organ rejection were reported. Without unvaccinated controls however, it is not possible at this time to determine if receipt of a third COVID-19 vaccine dose could potentially be associated with an increased risk of rejection in this population. No serious adverse events were deemed to be associated with the vaccine. Limitations of these studies include small sample sizes, short follow up periods and heterogeneous populations/vaccine schedules. Due to the small size of these studies and limited follow-up times, the impact of additional doses on rare adverse events in these populations are unknown.

The risk of myocarditis and/or pericarditis following receipt of an mRNA COVID-19 vaccine is currently reported more commonly after second doses compared to first doses. The risk of myocarditis and/or pericarditis associated with an additional dose of an mRNA vaccine, including when given to immunocompromised individuals, is unknown at this time. NACI is continuing to monitor the evidence and will update recommendations as information becomes available.
 

 

The additional or third dose recommended for moderately to severely immunocompromised persons should be distinguished from that of a booster dose. The intent of a booster dose is to restore protection that may have waned over time in individuals who responded adequately to an initial 1- or 2-dose primary vaccine series. Additional doses beyond the standard primary vaccine series, such as being recommended for those moderately to severely immunocompromised, provide an opportunity for individuals who may not have achieved an adequate level of protection from the standard primary vaccine series to develop a better immune response.

 

 

‎HSCT generally involves the ablation of the bone marrow followed by re-implantation of the person’s own stem cells (autologous HSCT) or stem cells from a donor (allogeneic HSCT). HSCT recipients should be viewed as "never immunized" and require re-immunization after transplant because the ablation of hematopoietic cells in the bone marrow pre-transplant eliminates most or all immune memory.5   


COVID-19 re-immunization of HSCT recipients should occur with a three dose primary series of a COVID-19 mRNA vaccine.6   

As a result of the prolonged period of immune suppression following transplantation, revaccination with inactivated vaccine is typically recommended 6-12 months post-transplant, however for certain vaccines such as influenza and COVID-19 vaccines, revaccination can occur as early as 3 months post-transplant.  The HSCT specialist will determine the appropriate time to commence immunizations and will provide written guidance to the client for sharing with the immunizing health care provider.

Similarly, CAR-T cell therapy recipients should be considered as “never immunized” as this therapy targets lymphocytes. COVID-19 re-immunization of CAR-T cell therapy recipients should occur with a three dose primary series with a COVID-19 mRNA vaccine.  

Due to prolonged period of immune suppression following CAR-T cell therapy, the revaccination with inactivated vaccine is typically recommended 6-12 months post therapy, however for certain vaccines such as influenza and COVID-19 vaccines, revaccination can occur as early as 3 months after CAR-T cell therapy.

For more information see:

 
1. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide: COVID-19 Chapter. 2022 January 14 [cited 2022 February 8] Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-26-covid-19-vaccine.html


2. Barda N, Dagan N, Balicer RD. BNT162b2 mRNA Covid-19 Vaccine in a nationwide mass vaccination setting. Reply. N Engl J Med. 2021 May 20;384(20):1970. doi: 10.1056/NEJMc2104281.


3. Chodick G, Tene L, Rotem RS, Patalon T, Gazit S, Ben-Tov A, et al. The effectiveness of the TWO-DOSE BNT162b2 vaccine: analysis of real-world data. Clin Infect Dis. 2021 May 17:ciab438. doi: 10.1093/cid/ciab438.


4. Whitaker HJ, Tsang RSM, Byford R, Andrews NJ, Sherlock J, Pillai PS, et al. Pfizer-BioNTech and Oxford AstraZeneca COVID-19 vaccine effectiveness and immune response among individuals in clinical risk groups. Preprint posted on khub. 2021 Jul 9. https://khub.net/documents/135939561/430986542/RCGP+VE+riskgroups+paper.pdf/a6b54cd9-419d-9b63-e2bf-5dc796f5a91f.


5. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Canadian Immunization Guide: Immunization of immunocompromised persons. 2022 May 9 [cited 2023 Feb 1]. Available from:
https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-3-vaccination-specific-populations/page-8-immunization-immunocompromised-persons.html

6. Public Health Agency of Canada [Internet]. Ottawa (ON); Public Health Agency of Canada. National Advisory Committee on Immunization (NACI). Updated guidance on COVID-19 vaccine booster doses in Canada. 2022 October 7 [Cited 2023 Feb 1]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/immunization/national-advisory-committee-on-immunization-naci/guidance-covid-19-vaccine-booster-doses.pdf

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Allergic event following a dose of COVID-19 vaccine

 
As of July 22, 2022 a total of 87,040,246 COVID-19 vaccine doses have been administered in Canada. There have been 49,921 adverse event reports with 39,874 considered non-serious and 10,047 considered serious. Of the serious reports, 863 severe allergic reactions or anaphylaxis have been detected. More information about reported adverse events following COVID-19 vaccine can be found on Health Canada’s Reported side effects following COVID-19 vaccination in Canada page. 

In BC, from December 13, 2020 to July 30, 2021 there have been a total of 12,177,643 COVID-19 vaccine doses administered. There have been 5,821 adverse events reported following COVID-19 vaccination with 449 (7.7%) meeting serious definition for a rate of 3.7 per 100,000 doses administrered. Of these, 422 individuals wre admitted to hospital, including 2.9% of cases reported as anayphylaxis.  More information about B.C.’s reports on adverse events can be found on BCCDC’s Vaccine Safety page. 

Reports of reactions to COVID-19 vaccines have increased concerns about their safety for individuals with allergies. The Canadian Society of Allergy and Clinical Immunology (CSACI) guidelines stress that there is a low risk for allergic reactions to vaccines, and non-allergic reactions to vaccines are more common than allergic reactions. In addition, non-allergic reactions to vaccines also include anxiety-related adverse events that can mimic allergic reactions.1 It is important to note that other, less serious reactions may mimic allergic reactions such as vasovagal syncope which are not contraindications to further vaccination.2 

Additional information regarding allergies and COVID-19 vaccine for the public can be found in the CSACI’s COVID-19 Vaccines FAQ resource.
 

 
It is important to first determine whether the reaction was an anaphylactic reaction. If an individual experienced a serious adverse event following immunization (AEFI), an AEFI report may be available in the provincial immunization data system. The AEFI report will contain details about the AEFI as well as the Medical Health Officer (MHO) recommendation on further immunization. 

Although anaphylaxis occurs rarely after vaccination, it is potentially life threatening and requires immediate treatment. It is characterized by sudden onset, rapid progression of signs and symptoms and is set apart from simple allergic reactions by the simultaneous involvement of several organ systems. Anaphylaxis that has been proven to be causally associated with vaccines is estimated at a frequency of 1.3 episodes per 1,000,000 doses of vaccines administered.3 Very rare cases of severe immediate reactions (e.g., anaphylaxis) following vaccination with COVID-19 vaccines have been reported in countries throughout the world with an incidence estimated between 2 to 7.9 cases per million doses of vaccine administered.4 There have been no fatalities nor long-term morbidity described with these events.5  Refer to the Brighton Collaboration Anaphylaxis: Case Definition Companion Guide and the Anaphylaxis: Case Definition Pictorial Algorithm for additional information.

A history of an anaphylactic reaction to any component of the vaccine is generally considered a contraindication to receiving the same vaccine or another COVID-19 vaccine of the same platform. For example: for individuals with a contraindication to a component such as polyethylene glycol found in an mRNA COVID-19 vaccine (e.g., Pfizer-BioNTech and Moderna) a COVID-19 vaccine from a different platform such as an adenoviral vector vaccine (e.g., AstraZeneca) should be considered followed by an observation period of at a least 30 minutes after immunization.

The checklist below can be used as a tool to assist health care providers to determine how to proceed when an individual reports an allergic reaction following a COVID-19 vaccine.
  • Was the event considered a severe allergic reaction or physician-diagnosed anaphylaxis?
  • Is there a history of anaphylactic reaction to any component of COVID-19 vaccine? 
  • Was the event reported to public health as an AEFI?
  • If reported to public health, is an MHO recommendation available? 
  • Did the MHO recommendation indicate that a COVID-19 vaccine from a different vaccine platform be provided? 
 

 
A potential allergen found in the COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna) is polyethylene glycol (PEG). 
  • Polyethylene glycol (PEG) can also be found in: cosmetics, skin care products, contact lens care solutions, cough syrup, laxatives, and bowel preparation products for colonoscopy. PEG is also used as an additive in some processed foods and drinks. However, no cases of anaphylaxis to PEG in foods and drinks have been reported.
A potential allergen found in the COVID-19 adenoviral vector vaccines (AstraZeneca/COVISHIELD and Janssen) and the Novavax vaccine is polysorbate 80. 
  • Polysorbate 80 can also be found in cosmetics and medical preparations which may include: vitamin oils, tablets, and anticancer agents.
More information and full lists of the components present in each COVID-19 vaccine can be found in the BC Immunization Manual, Part 4 – Biological Products, COVID-19 vaccines.
 

 
 

Any adverse event including an allergic reaction following a COVID-19 vaccine dose, should be reported to public health to be investigated by a medical health officer (MHO) or MHO designate who will provide a recommendation on further vaccination. Adverse events following immunization (AEFI) reports and recommendations can be accessed from the provincial immunization data system. The individual who experienced an AEFI that was reported to public health will be notified of the MHO recommendations on further immunization. The recommendations will also be sent to their most responsible health care provider. ‎


Very rare cases of severe immediate allergic reactions (e.g., anaphylaxis) have been reported following immunization with COVID-19 mRNA vaccines. History of an anaphylactic reaction to any component of the vaccine is generally considered a contraindication. However, for individuals with a history of anaphylactic reaction to a previous dose of an mRNA COVID-19 vaccine, administration of a subsequent dose in the series may be offered with the same vaccine or the same mRNA platform if a risk assessment deems that the benefits outweigh the potential risks for the individual and if informed consent is provided.  Prior to re-vaccination, consultation with an allergist or another appropriate physician (e.g., Medical Health Officer) is advised. If re-vaccinated, vaccine administration should be done in a controlled setting with expertise and equipment to manage anaphylaxis, with an extended period of observation of at least 30 minutes after re-vaccination.

The risk of a severe immediate allergic reaction after re-immunization appears to be low and no long-term morbidity has been associated with re-vaccination.6  In addition, recent studies have shown that most of the individuals who had these reactions after a previous dose of mRNA vaccine can be safely re-vaccinated with the same vaccine or another mRNA COVID-19 vaccine.7,8,9,10 


Alternatively, such individuals may be offered Novavax COVID-19 vaccine. A viral vector COVID-19 vaccine should only be considered when all other authorized COVID-19 vaccines are contraindicated or have been refused, due to the reduced effectiveness and the possible adverse effects specifically associated with viral vector vaccines (e.g., Thrombosis with Thrombocytopenia Syndrome [TTS]).

If a non-mRNA vaccine is recommended or requested, the client should call 1-833-838-2323 to book an appointment. Due to small supplies of these vaccines in the province, they will be directed to the appropriate site for receipt of the respective vaccine. 

 

Any health professional who is aware of an adverse event following immunization must report the event to the medical health officer as per the Public Health Act. Information on AEFI reporting can be found on the BCCDC COVID-19 Vaccination Health Care Provider Toolkit on the Adverse Events Following Immunization (AEFIs) page. More information about reporting anaphylaxis and other allergic reactions can be found in the BC Immunization Manual Part 5 - Adverse Events Following Immunization. In addition, the Report of Adverse Event Following Immunization is a shortened two page form available for non-public health professionals reporting AEFI.

 

 

1. Vander Leek TK, Chan ES, Connors L et al. COVID-19 vaccine testing & administration guidance for allergists/immunologist from the Canadian Society of Allergy and Clinical Immunology (CSACI). Allergy Asthma Clin Immunol 17, 29 (2021).  https://doi.org/10.1186/s13223-021-00529-2


2. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. Appendix A. 2021 Jul 22 [cited 2021 Sep 23]. Available from:

https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html


3. Anaphylaxis and other Acute Reactions following Vaccination: Canadian Immunization Guide-Canada.ca [Internet]. 2020. Available from:

https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-2-vaccine-safety/page-4-early-vaccine-reactions-including-anaphylaxis.html                                                                                                                         
4. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. [cited 2021 Dec 7]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html

5. Canadian Society of Allergy and Clinical Immunology [Internet]. Orleans (ON): Canadian Society of Allergy and Clinical Immunology. COVID-19 vaccine testing & administration guidance for allergists/immunologists from CSACI. 2021 November 14 [cited 2021 December 7]. Available from: https://csaci.ca/wp-content/uploads/2021/11/2021-11-15-UPDATE-COVID-19-Vaccine-Testing-Administration-Guidance.pdf
  
6. Public Health Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Summary of National Advisory Committee on Immunization (NACI) statement: Recommendations on the use of COVID-19 vaccines. 2021 Oct 22 [cited 2021 Dec 7]. Available from: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines/summary-october-22-2021.html 
 
7. Krantz MS, Kwah JH, Stone CA Jr, Phillips EJ, Ortega G, Banerji A, et al. Safety evaluation of the second dose of messenger RNA COVID-19 vaccines in patients with immediate reactions to the first dose. JAMA Intern Med. 2021 Jul 26. doi: 10.1001/jamainternmed.2021.3779. 
  
8. Krantz MS, Bruusgaard-Mouritsen MA, Koo G, Phillips EJ, Stone CA,Jr, Garvey LH. Anaphylaxis to the first dose of mRNA SARS-CoV-2 vaccines: Don't give up on the second dose! Allergy. 2021 Sep;76(9):2916,2920. doi: 10.1111/all.14958.
  
9. Kessel A, Bamberger E, Nachshon L, Rosman Y, Confino-Cohen R, Elizur A. Safe administration of the Pfizer-BioNtTech COVID-19 vaccine following an immediate reaction to the first dose. Allergy. 2021 Aug 9. doi: 10.1111/all.15038. 
  
10. Kelso JM. Misdiagnosis of systemic allergic reactions to mRNA COVID-19 vaccines. Ann Allergy Asthma Immunol. 2021 Jul;127(1):133,134. doi: 10.1016/j.anai.2021.03.024.


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