Clinicians should consult with their local Medical Health Officer with questions, concerns or for guidance related to cases suspected of COVID-19 infection.
Surveillance case definitions are intended for public health surveillance and reporting purposes and may not apply to clinical practice.
A person with laboratory confirmation of infection with the virus that causes COVID-19 performed at a community, hospital or reference laboratory (NML or a provincial public health laboratory) running a validated assay. This consists of detection of at least one specific gene target by a NAAT assay (e.g. real-time PCR or nucleic acid sequencing).1-3
- Close contact4 with a confirmed case of COVID-19,
- Lived in or worked in a closed facility known to be experiencing an outbreak of COVID-19 (e.g. long-term care facility, prison).
A person (who has had a laboratory test):
- with fever (over 38 degrees Celsius) or new onset of (or exacerbation of chronic) cough
- who meets the COVID-19 exposure criteria5 and in whom a laboratory diagnosis of COVID-19 is inconclusive.1,6,7
1. NAATs must be validated for detection of the virus that causes COVID-19.
2. Positive laboratory tests during early stages of testing (e.g. first 10 positive tests) at a non-reference laboratory require additional testing at a reference laboratory for confirmation.
3. Laboratory tests are evolving for this emerging pathogen, and laboratory testing recommendations will change accordingly as new assays are developed and validated.
4. A high-risk close contact is defined as a person who:
- provided direct care for the case, including healthcare workers, family members or other caregivers, or who had other similar close physical contact (e.g., intimate partner) without consistent and appropriate use of personal protective equipment, OR
- lived with or otherwise had close face to face contact (within 2 metres) with a probable or confirmed case for more than 15 minutes (may be cumulative, i.e., multiple interactions) up to 48 hours prior to symptom onset, OR
- had direct contact with infectious body fluids of a probable or confirmed case (e.g., was coughed or sneezed on) while not wearing recommended PPE, OR
- has been identified by the local MHO as a possible contact.
5. Exposure criteria: In the 14 days before onset of illness, a person who:
- Traveled to an affected area (including inside Canada) OR
- Had close contact with a person with acute respiratory illness who traveled to an affected area (including inside Canada) within 14 days prior to their illness onset OR
- Participated in a mass gathering identified as a source of exposure (e.g., conference) OR
- Had laboratory exposure to biological material (e.g. primary clinical specimens, virus culture isolates) known to contain COVID-19.
Note: Other exposure scenarios not specifically mentioned here may arise and may be considered at MHO discretion (e.g. history of being a patient in the same ward or facility during a nosocomial outbreak of COVID-19).
6. Inconclusive is defined as an indeterminate test on a single or multiple real-time PCR target(s) without sequencing confirmation or a positive test with an assay that has limited performance data available.
7. An indeterminate result on a real-time PCR assay is defined as a late amplification signal in a real-time PCR reaction at a predetermined high cycle threshold value. This may be due to low viral target quantity in the clinical specimen approaching the limit of detection (LOC) of the assay, or may represent nonspecific reactivity (false signal) in the specimen. When clinically relevant, indeterminate samples should be investigated further in the laboratory (e.g. by testing for an alternate gene target using a validated real-time PCR or nucleic acid sequencing that is equally or more sensitive than the initial assay or method used) or by collection and testing of another sample from the patient with initial indeterminate result.
8. Cases with indeterminate lab results and an epidemiologic link to a
confirmed/probable case (e.g., close contact, or exposure to closed facility
known to be experiencing an outbreak) should be reported as probable-lab cases.