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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 may be updated as new information and new COVID-19 vaccines become available in BC.

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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:
While preventive measures such as physical distancing, frequent handwashing, and wearing a mask help to reduce the risk of exposure and transmission of SARS-CoV-2, the virus that causes COVID-19 infection and disease, these measures alone are not enough. The combination of COVID-19 vaccination and following BCCDC’s prevention measures offer the best protection from COVID-19.  Ending this pandemic requires all the tools we have available, including, most importantly, vaccination. 

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.

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.

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.


COVID-19 vaccines in Canada

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General questions

‎There is currently no evidence on the need for booster doses of COVID-19 vaccine after the vaccine series is complete. As the first participants in clinical trials were vaccinated at the end of July 2020, and the first vaccines being approved in December 2020, only short-term clinical trial data are available. Clinical trial participants will continue to be monitored for a total of at least two years to understand how long immunity lasts after vaccination.

There are also several research and surveillance priorities that are occurring with respect to the efficacy, effectiveness, immunogenicity and safety of the COVID-19 vaccines, which include population effectiveness and medium and long-term duration of protection of a complete series of COVID-19 vaccine. The degree to which these vaccines protect against COVID-19 one, two or more years after vaccination will be determined with ongoing vaccine effectiveness surveillance.2

‎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. At this time, there is insufficient evidence on the duration of protection of COVID-19 vaccines in preventing infection and reducing transmission of SARS-CoV-2 to recommend discontinuation of public health measures.  It is expected, however, that over time with more information about the impact of vaccination on COVID-19 transmission that there will be changes to the current prevention and control measures. 


‎The median period of follow up of vaccine and placebo recipients from phase 3 clinical trials was 2 months.  Protection beyond this period is expected, and 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 information will also 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 eventually through the long-standing Sentinel Physician 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.


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In B.C., individuals turning 12 years of age within the calendar year and older, are eligible to receive COVID-19 vaccination. 

At this time, no COVID-19 vacccine has been approved for use in children under the age of 12 in Canada. Clinical trials are underway to determine if COVID-19 vaccines are safe and effective in infants and children under 12, and whether young children need smaller doses. ‎

In B.C., more information on COVID-19 vaccine eligibility can be found on the BCCDC website at: 
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COVID-19 mRNA vaccines

Additional information specific to the mRNA vaccines currently authorized for use in Canada can be found in the National Advisory Committee (NACI) Statement, Recommendations on the use of COVID-19 Vaccines, Appendices A & B.

Messenger RNA (mRNA) is the ‘blueprint’ that cells use to synthesize proteins required for our physiology. The two newly approved COVID-19 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. 3 4 5     

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. 


Pfizer-BioNTech COVID-19 vaccine 

The estimated vaccine efficacy at least 7 days after Dose 2 was 94.6% (95% CI: 89.9 to 97.3%), with 9 laboratory confirmed symptomatic COVID-19 cases identified among vaccine recipients (N=19,965) compared to 169 cases among placebo recipients (N=20,172). The vaccine efficacy at least 14 days after Dose 2 in this population was comparable (94.4%, 95% CI: 89.1 to 97.3%). 

When stratified by age, vaccine efficacy against COVID-19 from 7 days after Dose 2 was between 93.7% (>55 years) and 95.6% (16 to 55 years). In individuals ≥65 years of age, vaccine efficacy was 94.7% (95% CI: 66.7 to 99.9%). In participants ≥75 years of age, the observed vaccine efficacy was 100% compared to placebo (95% CI: -13.1 to 100.0%), however this must be interpreted with caution as there were few cases identified in this age group, accounting for the wide confidence intervals. The estimated vaccine efficacy against confirmed COVID-19 from 7 days after Dose 2 was greater than 91% (between 91.7% and 100.0%) in all subgroups stratified by "at risk" status (e.g., presence of 1 or more comorbidities). The estimated vaccine efficacy against confirmed COVID-19 illness from 7 days after Dose 2 was greater than 89% for all races (89.3 to 100%) and 94% for all ethnicities included in the sub-analysis (94.4 to 95.4%).1

Moderna COVID-19 vaccine 

The estimated vaccine efficacy at least 14 days after Dose 2 was 94.1% (95% CI: 89.3 to 96.8%), with 11 confirmed COVID-19 cases identified among vaccine recipients (n= 14,134) compared to 185 confirmed COVID-19 cases among placebo recipients (n= 14,073). 

When stratified by age, vaccine efficacy against COVID-19 from 14 days after Dose 2 for those 18 to < 65 years of age was 95.6% (95% CI: 90.6 to 97.9%). For those > 65 years of age, vaccine efficacy was 86.4% (95% CI: 61.4 to 95.2%). For those > 75 years of age, vaccine efficacy was 100% however; this must be interpreted with caution as there were few cases identified in this age group.6

‎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 7


Dosing and scheduling

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

For optimal response, immunizers should observe recommended intervals as much as possible, however, doses given earlier than recommended may still be considered valid and need not be repeated if minimum intervals are observed. The recommended minimum intervals between doses for the COVID-19 mRNA vaccines are as follows:

  • Pfizer-BioNTech: 18 days 
  • Moderna: 21 days

NACI recommends that the vaccine series be completed with the same COVID-19 vaccine product. However, the spike proteins that encode the authorized mRNA vaccines have the same sequence and are stabilized in the same manner to remain in the pre-fusion confirmation, though other vaccine components like the lipid nanoparticle may be different.


If the vaccine product used for a previous dose is not known, attempts should be made to identify which vaccine was given for the first dose in order to give the same product for the second dose. If the same product is not readily available, the vaccine series can only be complelted with a similar type of COVID-19 vaccine (i.e., mRNA vaccine). Readily available means it is easily available at the time of vaccination without delay or vaccine wastage. Such a series should be considered as valid, without need to restart a two dose series with a new product. 

On June 1st 2021, NACI recommended that individuals who received a first dose of of the AstraZeneca or COVISHIELD vaccine could receive an mRNA vaccine for their second dose, unless there are contraindications to the mRNA vaccine.


Yes. A 21-gauge needle or narrower is recommended to prevent a larger opening in the vial stopper that may allow vaccine to leak.9

Yes. After adding the diluent into the vaccine vial, withdraw 1.8 mL of air from the vaccine vial into the empty diluent syringe prior to removing the needle and attached syringe from the vial.  This will prevent loss of vaccine from the vial through forceful expulsion under pressure. 9 ‎


An additional dose can be withdrawn in its entirety, if the volume of residual vaccine allows, or constituted from up to three separate vials with residual vaccine, after withdrawal of the full number of labelled doses from the Pfizer (labelled 6 doses of 0.3 mL each/vial) or Moderna (labelled 10 doses of 0.5 mL each/vial or 14 doses of 0.5 mL each/vial for the US-labelled product) vaccines.


Following withdrawal of all available doses from each vial, the residual vaccine from up to three vials can be withdrawn into the same syringe to constitute a full dose provided the vials are from the same manufacturer and have the same lot number. More information can be found in the BC Immunization Manual, Part 4 – Biological Products: Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines – Addendum: Pooling residual vaccine from up to three vials to constitute an extra dose.


Withdrawal of even 6 doses from a single vial of the Pfizer-BioNTech vaccine is dependent, in part, on the type of syringes or needles used to withdraw the vaccine from the vial. Low dead-volume syringes and/or needles should be used if available, as standard syringes and needles may not facilitate the extraction of the sixth dose from a single vial.  Similarly for Moderna, the withdrawal of a complete 0.5 mL dose after 10 or 14 doses have been removed from the vial is dependent, in part, on the type of syringes and needles, and low dead-volume syringes and/or needles may be needed to extract an additional dose.

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.10 11  These events are not reportable unless they meet the reporting criteria outlined in the BC Immunization Manual, Part 5: Adverse Events Following Immunization. 


Contraindications and precautions

The authorized COVID-19 mRNA vaccines are contraindicated in 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 adenovirus vector COVIID-19 vaccine and observed for at least 30 minutes after immunization.
Of note, clinical trials of the authorized COVID-19 vaccines excluded individuals with a history of severe adverse reaction associated with a vaccine and/or severe allergic reaction (e.g., anaphylaxis) to any component of the vaccine. 

For a list of components in the vaccine and packaging consult the respective COVID-19 mRNA vaccine product monographs found at:

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. ‎


The Canadian Society for Allergy and Clinical Immunology has issued updated guidance for testing and administration of COVID-19 vaccines in allergic individuals.12  In situations of suspected hypersensitivity or non-anaphylactic allergy to COVID-19 vaccine components, consultation with an allergist is advised. If there is a specific concern about a possible allergy to a component of the COVID-19 vaccine being administered, an extended period of observation post-vaccination of 30 minutes may be warranted; alternately, the vaccine can be administered in an emergency room setting, also with a prolonged observation period.

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. In the US data, they have noted that the observed rates exceed what would be expected (given that these are inflammatory disorders of the lining of the heart and heart muscle, respectively, and occur for a variety of reasons including in association with viral infections). 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 events have occurred more frequently after the second dose at a rate of about 1 per 100,000 second doses, and have been observed mostly in males under 30 years of age, usually within a week of vaccination. Most cases recover fully with conservative treatment. 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, which is yet to be detected as occurring above the expected frequency in our safety reports in BC and Canada. This is an emerging safety signal and will need to be studied further. 

The 2nd dose of mRNA COVID-19 vaccine should be deferred in those who experienced a physician-diagnosed myocarditis or pericarditis event following the first dose with no other cause identified, until further information about the risk of recurrence is available. 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

‎As neither mRNA vaccine contains preservatives to prevent microbial contamination, the Pfizer-BioNTech vaccine must be used within 6 hours of dilution and the Moderna vaccine must be used within 24 hours of first puncture to the vial.



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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Non-replicating viral vector-based (adenovirus) COVID-19 vaccines

AstraZeneca, COVISHIELD and Janssen COVID-19 vaccines

Both AstraZeneca and COVISHIELD COVID-19 vaccines are viral vector-based vaccines that contain a modified version of a replication-deficient chimpanzee adenovirus (ChAdOx1). The Janssen COVID-19 vaccine is also a viral vector-based vaccine which uses a modified replication-deficient human adenovirus type 26 vector. These are different viruses than the one that causes COVID-19. These vaccines stimulate the body's natural defenses to protect against the SARS-CoV-2 virus. Inside the shell of the modified virus, there is material from the virus that causes COVID-19. This is called a “viral vector.” Once the viral vector has entered the cells involved in the immune response, the genetic material gives the cells instructions to make the COVID-19 spike protein, the same antigenic target to which immunity is generated by the mRNA vaccines. The protein is produced intracellularly and placed on the surface of the cell, generating both cellular and humoral (T-lymphocytes and B-lymphocytes) immunity.‎



AstraZeneca/COVISHIELD COVID-19 Vaccine

The estimated vaccine efficacy at least 15 days after Dose 2 in study participants who received the standard dose (SD) vaccine for both doses was 62.5% (95% CI: 50.7 to 71.4%), based on identification of 71/6,085 (1.2%) cases in vaccine recipients and 186/6,073 (3.1%) in controls. The estimated vaccine efficacy by age was 63.1% (51.1 to 72.1%) in study participants 18-64 years of age and 50.7% (-65.8 to 85.4%) in participants ≥ 65 years of age (NACI). It is important to note, however, that Phase 3 clinical trials of the AstraZeneca vaccine had a very small number of participants over 65 years of age that contracted COVID-19 to determine the efficacy of the vaccine in this age group.


Estimates of vaccine efficacy against hospitalization > 22 days after dose 1 was 100% (NACI). 


An exploratory analysis examined the potential effect of the interval between dose 1 and 2 on vaccine efficacy in study participants receiving the SD/SD vaccine regimen. This analysis indicated that efficacy was higher in those with a longer interval (> 12 weeks) at 81.3% (95% CI 60.3 to 91.2).13


A further exploratory analysis at > 22 days after the first dose found that a single standard dose vaccine provided protection against primary symptomatic COVID-19 in the first 90 days with an efficacy of 76.0% (95% CI 59.3 to 85.9), with no evidence of waning of protection during the same time period.14


Because this vaccine was not tested in head to head clinical trials against the mRNA vaccines, the results of the efficacy studies are not directly comparable. The vaccines were studied in different populations at different times. Both of the mRNA vaccines and ChAdOx1-S vaccine provide high levels of protection against severe COVID-19 disease.

Janssen COVID-19 Vaccine

The estimates of vaccine efficacy against confirmed symptomatic moderate to severe/critical COVID-19 infection with onsets ≥14 days and ≥28 days post-vaccination are 66.9% and 66.1%, respectively.

The estimates of vaccine efficacy against confirmed symptomatic severe/critical COVID-19 infection are 76.7% with onset ≥14 days post-vaccination and 85.4% with onset ≥28 days post-vaccination. The efficacy against confirmed symptomatic severe/critical COVID-19 infection with onset ≥14 days was calculated for four age groups: 18–59 (80.5%), 18–64 (78%), ≥60 (68.5%), ≥65 (69.9%). For confirmed symptomatic severe/critical COVID-19 infection with onset ≥28 days, the efficacy calculated for the same age groups was: 18–59 (91.7%), 18–64 (92.9%), ≥60 (70.3%), ≥65 (50.1%).15

Dosing, scheduling and administration

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

(Click to enlarge)‎

AstraZeneca and COVISHIELD COVID-19 vaccines are interchangeable within the vaccine series, however, these vaccines are no longer being offered as a first dose, unless there is a contraindication to the mRNA vaccines, or as advised by the Medical Health Officer or an allergist. 

On June 1, 2021, NACI recommended that individuals who received a first dose of the AstraZeneca/COVISHIELD vaccine may receive either AstraZeneca/COVISHIELD vaccine or an mRNA vaccine (Pfizer-BioNTech or Moderna) for their second dose unless contraindicated.

In the event that an individual receives one dose of the AstraZeneca/COVISHIELD vaccine and is unable to receive the same type of viral vector vaccine for the second dose, receiving the Janssen vaccine would be considered restarting a vaccine series, as one dose of the Janssen vaccine is considered to be a complete series.

Individuals receiving the AstraZeneca/COVISHIELD and Janssen vaccines should be reassured that adverse events are very rare, and COVID-19 infections can lead to significant complications, including a range of clotting disorders. Those who have been vaccinated with either product in the last month, should monitor for symptoms and seek immediate medical attention in the very unlikely event that they develop: 

  • Prolonged headache beginning 4 or more days after vaccination
  • Blurred vision
  • Difficulty speaking
  • Seizure
  • Difficulty moving parts of the body 
  • Shortness of breath
  • Chest pain
  • New severe swelling, pain or colour change of an arm or a leg
  • Persistent abdominal pain
  • Abnormal bruising, reddish or purple spots or blood blisters under the skin
  • Bleeding beyond site of vaccination 
It is important to note that although rare, the outcome of TTS can be serious including fatal. In addition to timely diagnosis and management, clinicians who identify vaccine recipients with TTS should promptly report such cases to the adverse events following immunization system in B.C.

In B.C., these vaccines are no longer being offered as a first dose, and individuals who have received 1 dose of AstraZeneca or COVISHIELD vaccine may receive either AstraZeneca/COVISHIELD vaccine or an mRNA vaccine (Pfizer-BioNTech or Moderna) for their second dose, unless contraindicated.

Contraindications and Precautions

The AstraZeneca/COVISHIELD and Janssen COVID-19 
vaccines are contraindicated in individuals with:
  • A history of anaphylactic reaction to a previous dose of the vaccine or to any component of the vaccine.
  • A history of thrombosis with thrombocytopenia following a previous dose of an adenovirus vector COVID-19 vaccine. These individuals should be offered an mRNA vaccine.
  • A history of capillary leak syndrome.
For a list of components in the vaccine see Section 6 Dosage Forms, Strengths, Composition and Packaging of the respective viral vector-based vaccine product monographs found at:


The AstraZeneca/COVISHIELD and Janssen COVID-19 vaccines contain polysorbate 80 which can be found in various products such as cosmetics and medical preparations including vitamin oils, tablets, and anticancer agents.

In situations of suspected hypersensitivity or non-anaphylactic allergy to COVID-19 vaccine components, consultation with an allergist is advised. If there is a specific concern about a possible allergy to a component of the COVID-19 vaccine being administered, an extended period of observation post-vaccination of 30 minutes may be warranted; alternately, the vaccine can be administered in an emergency room setting, also with a prolonged observation period.‎

In late March, a safety signal emerged in several European countries of an unusual syndrome of acute venous or arterial thrombosis, new onset thrombocytopenia with or without hemorrhage with onset of symptoms by around 14 days after vaccination with AstraZeneca COVID-19 vaccine. Affected sites have included central venous sinuses, portal vein, splanchnic veins, and splenic veins. While the first case reports appeared largely in young to mid-adult age women, later updates indicated the occurrence of the event in both sexes, although with a preponderance of cases in females under 55 years old. Because denominator data on vaccine recipients have not been made available, accurate assessment of rates by age group and sex has been hampered. 

In early April the European Medicines Agency issued a warning about the occurrence of this syndrome, with information for both clinicians and recipients.16  Subsequently Health Canada also added a warning for both AstraZeneca COVID-19 vaccine and COVISHIELD.17  Some countries have not reintroduced the use of the vaccine since the recognition of these events, and others have advised against use below a certain age. While the Canadian National Advisory Committee on Immunization has issued updated recommendations, which currently allow for immunization of those aged 30 and older in moderately high and high COVID-19 incidence communities, following a benefit-risk assessment,these

vaccines are approved for individuals aged 18 years and older. 

This adverse event has been called Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT), Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT) and more recently Thrombosis with Thrombocytopenia Syndrome (TTS) and is estimated to occur in approximately 1 in 50,000 vaccine recipients. The frequency of TTS following a second dose of AstraZeneca or COVISHIELD vaccine is currently reported as approximately 1 per 600,000. Epidemiological information about the syndrome is still evolving, and a similar syndrome identified in the United States appears to be associated with the Janssen (Johnson & Johnson) adenovirus vector vaccine.18 The biological mechanism is thought to be similar to that of spontaneous heparin-induced thrombocytopenia, as it occurs outside of the context of heparin treatment. The Ontario Science Table COVID-19 Advisory has issued diagnostic and treatment guidelines.19 The Updated Recommendation for AstraZeneca and COVISHIELD Vaccines letter dated March 29, 2021 provides recommendations for physicians whose patients received COVISHIELD/AstraZeneca COVID-19 vaccine.

While not a contraindication, individuals who have experienced cerebral venous sinus thrombosis (CVST) with thrombocytopenia, unrelated to adenovirus vector COVID-19 vaccination, or heparin induced thrombocytopenia (HIT), should only receive an adenovirus vector COVID-19 vaccine if the benefits outweigh the potential risks and an mRNA vaccine is unavailable.


Vaccine storage and handling

‎The viral vector vaccines should be stored refrigerated at temperatures of +2°C to +8°C, similar to other routine non-COVID-19 vaccines in BC. Information regarding the storage and handling of refrigerated vaccines can be found in the BC Immunization Manual, Appendix E – Management of Biologicals.  

Additional information, including standard operating procedures (SOPs) can be found on the COVID-19 Immunize BC Operations Centre: Standard Operating Procedures page.

Additional information

The AstraZeneca/COVISHIELD and Janssen vaccines are manufactured using human embryonic cells for the propagation of the virus that contains the genetic information for the SARS-CoV-2 spike protein. The AstraZeneca/COVISHIELD vaccine uses the kidney cell line HEK-293 that was isolated in the 1970s while the Janssen vaccine uses the retinal cell line PER.C6 that was isolated in 1985. The cell lines are used widely in academic research and in the pharmaceutical and biotechnology industries. 

Although these cell lines are used in the manufacturing process, the final vaccine does not contain any cells.

The Catholic Church has stated that receiving a COVID-19 vaccine that required fetal cell lines for production or manufacture is morally acceptable.

‎The Serum Institute of India (SII) was founded in 1966 and is the world’s largest vaccine manufacturer. It produces more than 1.5 billion doses of vaccines each year. Vaccines from SII are used in national immunization programs in approximately 170 countries around the world. The vaccines used in these programs include diphtheria, tetanus, pertussis, Haemophilus influenzae type b, hepatitis B, measles, mumps and rubella. The SII is accredited by the World Health Organization and its facilities are compliant with good manufacturing practice (cGMP); this ensures that the vaccines manufactured by the SII are safe for use, contain the specified ingredients and have the required potency. 

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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 will be 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 

Safety and efficacy of the COVID-19 vaccines was not studied in people who are pregnant or breastfeeding in the clinical trials for these vaccines, and studies are being performed during the post marketing period. 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 NACI20 and the Society of Obstetricians and Gynaecologists of Canada (SOGC)21 have pre-existing general recommendations that inactivated viral vaccines can be safely given in pregnancy. While the current NACI statement on COVID-19 vaccines is cautionary, 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.22 New data are beginning to emerge 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.23  

Both NACI and SOGC recommend that the pregnant or lactating person be informed about the lack of clinical trial data specifically designed to address the performance and safety of the vaccine in pregnancy and lactation. 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. There is no specific reason why healthy pregnant or lactating people or those with stable underlying chronic diseases such as those enrolled in the phase 3 clinical trials should not mount a good immune response to either vaccine. 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. 


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 a diminished immune response to the vaccine.

A complete COVID-19 vaccine series may be offered to individuals in the authorized age group if a risk assessment deems that the benefits outweigh the potential risks for the individual, and if informed consent includes discussion about the absence of evidence on the use of COVID-19 vaccine in these populations. 

Advise those who are immunosuppressed due to disease or treatment to have a discussion with the care provider who knows their condition the best, as they would be most familiar with the client’s disease and treatment. If such a client presents for immunization and indicates that they have had this discussion with their care provider and they understand the benefits and risks and limited evidence on the use of COVID-19 vaccine in these populations, this would be sufficient for the immunizer to proceed with vaccination.

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.24  

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. 
To date, there is insufficient evidence on the receipt of both a COVID-19 vaccine and anti-SARS-CoV-2 monoclonal antibodies or convalescent plasma for treatment or prevention. Therefore, timing of administration and potential interference between these two products are currently unknown. Administration of these products close together may result in decreased effectiveness of a COVID-19 vaccine and/or anti-SARS-CoV-2 monoclonal antibodies because the monoclonal antibodies have high affinity for the spike protein expressed by the vaccines. 

For persons who received monoclonal antibodies or convalescent plasma for treatment of COVID-19, at least 90 days should elapse prior to vaccination with a COVID-19 vaccine.  A second infection is unlikely to occur in that time period, and a period of 90 days or more will minimize the risk of blunting of the vaccine induced immune response, accounting for the estimated half-life of these treatments. 

People receiving other antibody therapies unrelated to COVID-19 treatment (e.g., IVIG, RhoGAM) may receive COVID-19 vaccine at the same time or any interval before or after these therapies, as these are deemed unlikely to interfere with the immune response to the vaccine.

Yes. NACI recommends that a complete series with a COVID-19 vaccine should be offered to individuals with prior PCR-confirmed SARS-CoV-2 infection. Reinfections reported to date have been rare within the first three months following infection. Whether such individuals require the full two dose series is being studied; currently, the full series is recommended in BC. ‎


Yes. General immunization guidelines support coadministration of other indicated vaccines at the same visit, at a different injection site(s). This includes both inactivated and live vaccines, if the individual is behind schedule or due to receive these vaccines, and if these are not contraindicated in their circumstances. If not given at the same visit, these vaccines can be given before or after the COVID-19 vaccine, without regard to the number of days or weeks of this interval.

While formal studies of coadministration have not been conducted yet, general guidelines on immunization are to use every visit as an opportunity to offer recommended vaccines.

There are currently no data to inform whether COVID-19 vaccines affect TST or IGRA results. However, there is a theoretical concern that COVID-19 vaccines may temporarily affect cell-mediated immunity, resulting in false-negative TST or IGRA test results. As such, tuberculin skin tests and IGRA tests should be administered and read before COVID-19 immunization or delayed for at least 4 weeks after immunization. COVID-19 immunization may take place at any time after all steps of the TST have been completed.25

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. However, 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.5
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.26  

As of May 27, 2021, the recommended interval between dose 1 and dose 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.

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.27 28 29 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. Some radiologists have recommended that routine imaging examinations including screening mammograms be scheduled before or at least 6 weeks after the vaccine dose in order to avoid misinterpretation of findings. 

The BC Cancer Agency recommends that scheduled screening mammograms should not be cancelled 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. For those scheduling their appointments in conjunction with recent receipt or future scheduling of COVID-19 vaccine, this information should be provided to the booking clerk so that the screening appointment can be made before vaccination or 6 weeks after vaccination.30

Individuals for whom there are clinical indications (such as identification of a new breast mass or short-interval treatment monitoring or management of complications) for imaging should not delay imaging because of recent vaccination. 

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.  

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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:


2. Children's Hospital of Philadelphia [Internet]. Philadelphia: Children's Hospital of Philadelphia; c2021. Questions and answers about COVID-19 vaccines. 2020 Dec 31 [cited 2021 Jan 8]. Available from:


3. 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:


4. 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:


5. 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:


6. 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:

7. Pfizer Canada ULC.  Pfizer-BioNTech COVID-19 Vaccine Product Monograph [Internet]. 2020 Dec 9 [cited 2021 February 19]. 26 p. Available from:


8. Moderna Therapeutics Inc. Moderna COVID-19 Vaccine  Product Monograph [Internet]. 2020 Dec 23 [cited 2021 Jan 5]. 19 p. Available from:


9. Pfizer-BioNTech COVID-19 Vaccine [Internet}. Kirkland (QC): Pfizer Canada ULC; c2021.Dosing and administration; 2020 Dec [cited 2020 Dec 22]. Available from:


10. 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:


11. 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


12. Canadian Society of Allergy and Clinical Immunology [Internet]. Orleans (ON): Canadian Society of Allergy and Clinical Immunology. SARS-CoV-2 vaccine testing & administration guidance for allergists/immunologists from CSACI. 2021 April 10 [cited 2021 April 29]. Available from:


13. Voysey M, Costa Clemens SA, Madhi SA, et al. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine  (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet [Internet]. 2021 Jan 9 [cited 2021 Mar 16];397(10269):99-111. Available from:


14. Voysey M, Costa Clemens SA, Madhi SA, et al. Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: A pooled analysis of four randomised trials. Lancet [Internet]. 2021 Mar 6 [cited 2021 Mar 16];397(10277):881-891. Available from:


15. Public Heath Agency of Canada [Internet]. Ottawa (ON): Public Health Agency of Canada. Recommendations on the use of COVID-19 vaccines. 2021 May 3 [cited 2021 May 14]. Available from:

16. European Medicines Agency. AstraZeneca's COVID-19 vaccine: EMA finds possible link to very rare cases of unusual blood clots with low blood platelets. April 7, 2021.


17. Health Canada. Recalls and Safety Alerts. Health Canada provides update on the AstraZeneca and COVISHIELD COVID-19 vaccines. Updated April 16, 2021. Accessed April 28, 2021.,headaches%20or%20blurred%20vision%3B%20or


18. Centers for Disease Control and Prevention. Atlanta GA. The Advisory Committee on Immunization Practices' (ACIP) updated recommendations on the use of the Janssen (Johnson & Johnson) COVID-19 vaccine. Accessed April 24, 2021. Available from:

19. Pai M, Grill A, Ivers N, et al. Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT) Following AstraZeneca COVID-19 Vaccination. March 26, 2021.

20. 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:


21. 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:


22. 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:


23. 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.

24. Canadian Rheumatology Association. Recommendations on COVID-19 vaccination in persons with autoimmune rheumatic disease. January 2021.


25. 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:


26. 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:


27. 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: 


28. 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:


29. 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:


30. BC Cancer. COVID-19 and Cancer Screening. Does the COVID-19 vaccine affect my screening mammogram? Accessed April 28, 2021.

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