Interim national case definition: Coronavirus disease (COVID-19)

Last Updated: April 2, 2020

On this page

• Preamble
• National surveillance case definitions for COVID-19
• Exposure criteria
• Mechanism of reporting

A. Preamble

At this time, the primary surveillance objective for COVID-19, is the detection of cases and identification of outbreaks in Canada. The secondary objective is to characterize the clinical and epidemiologic features of COVID-19 in order to better inform prevention and control efforts.

This document outlines surveillance case definitions for COVID-19 and provides instructions on reporting to the national level. Detailed information on detecting and reporting COVID-19 cases in Canada can be found in the Interim National Surveillance Guidelines for Coronavirus Disease (COVID-19).

Surveillance case definitions are provided for the purpose of standardized case classification and reporting to the Public Health Agency of Canada. They are based on the current level of epidemiological evidence and uncertainty, and public health response goals, and are subject to change as new information becomes available.

These surveillance case definitions are not intended to replace clinician or public health practitioner judgment in individual patient management, or intended to be used for the purpose of infection control triage.

Tests specific for COVID-19 can be performed in select laboratories (i.e. some provincial public health, hospital-based and community laboratories). During early stages of testing (e.g. until 10 positive specimens are encountered at an individual laboratory), conclusive diagnosis requires confirmation by Canada's National Microbiology Laboratory (NML) or a provincial public health laboratory by nucleic acid amplification tests (NAAT). Patients under investigation who meet the probable case definition remain so pending confirmation.

B. National surveillance case definitions for COVID-19

Provincial/Territorial public health authorities should report confirmed and probable cases of COVID-19 nationally to the Public Health Agency of Canada within 24 hours of their own notification.

Suspect case

A person with symptoms that include two or more of:

• Fever (signs of fever)
• Cough (new or exacerbated chronic)
• Sore throat
• Runny nose
• Headache
  

And

• Meets the exposure criteria
  Or
• Had close contact ^{Footnote 2} with a probable case of COVID-19

Note: COVID-19 may present as a co-infection with other pathogens.  At this time, the identification of one causative agent should not exclude COVID-19 where the index of suspicion ^{Footnote 3} may be high.

Probable

A person (who has had a laboratory test):

• with fever (over 38 degrees Celsius) or new onset of (or exacerbation of chronic) cough
  And
• who meets the COVID-19 exposure criteria and in whom a laboratory diagnosis of COVID-19 is inconclusive.

Or

A person (who has not had a laboratory test):

• With fever (over 38 degrees Celsius) or new onset of (or exacerbation of chronic) cough,
  And
  • Close contact ^{Footnote 2} with a confirmed case of COVID-19,
    Or
  • Lived in or worked in a closed facility known to be experiencing an outbreak of COVID-19 (e.g., long-term care facility, prison)

Notes:

• NAATs must be validated for detection of the virus that causes COVID-19.
• 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.
• 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.

Confirmed

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).

Notes:

• NAATs must be validated for detection of the virus that causes COVID-19.
• 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.
• Laboratory tests are evolving for this emerging pathogen, and laboratory testing recommendations will change accordingly as new assays are developed and validated.

C. Exposure criteria

In the 14 days^{Footnote 1} before onset of illness, a person who:

• Traveled to an affected area (including inside Canada)

Or

• Had close contact^{Footnote 2} with a person with acute respiratory illness who traveled to an affected area (including inside Canada) within 14 days prior to their onset of illness

Or

• Participated in a mass gathering identified as a source of exposure (e.g., conference) ^{Footnote 3}

Or

• Had laboratory exposure to biological material (e.g. primary clinical specimens, virus culture isolates) known to contain COVID-19.

D. Mechanism of reporting

Notification of Confirmed and Probable cases can be made to phac.hsfluepi.aspc@canada.ca during regular business hours (8:00am - 5:00pm ET). After regular business hours please contact the Public Health Agency of Canada's Health Portfolio Operations Centre (HPOC) Watch Office by phone (1-800-545-7661) or through the single window email: phac-aspc.hpoc-cops@canada.ca.