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

Last Updated: February 25, 2020

A. Preamble

At this time, the primary surveillance objective for COVID-19, recently identified as the cause of an atypical pneumonia outbreak, which began in the city of Wuhan, China, is early detection and containment. 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.

Initial tests specific for COVID-19 can be performed in select laboratories (i.e. some provincial public health and hospital-based laboratories); however, until further notice 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.

Person under investigation (PUI)

A person with fever and/or cough who meets the exposure criteria and for whom a laboratory test for COVID-19 has been or is expected to be requested.

Note: The surveillance mechanisms and systems for identifying a PUI may vary by jurisdiction according to perceived risk, resources, supporting structures and other context

Note: There is limited evidence on the likelihood of COVID-19 presenting 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:

with fever (over 38 degrees Celsius) and/or new onset of (or exacerbation of chronic) cough
AND
who meets the COVID-19 exposure criteria
AND
in whom laboratory diagnosis of COVID-19 is
- inconclusive,
- negative (if specimen quality or timing is suspect), or
- positive but not confirmed by the National Microbiology Laboratory (NML) or a provincial public health laboratory by nucleic acid amplification tests (NAAT).

Note: nucleic acid amplification tests must be validated for detection of the virus that causes COVID-19.

Note: Inconclusive is defined as a positive test on a single real-time PCR target without sequencing confirmation or a positive test with an assay that has limited performance data available.

Confirmed

A person with laboratory confirmation of infection with the virus that causes COVID-19 is performed at a reference laboratory (NML or a provincial public health laboratory), and consists of positive nucleic acid amplification tests (NAAT) on at least two specific genome targets or a single positive target with nucleic acid sequencing.

Positive laboratory tests at a non-reference laboratory require additional testing at a reference laboratory for confirmation.

Note: nucleic acid amplification tests must be validated for detection of the virus that causes COVID-19

Note: 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
OR
Had close contact^{Footnote 2} with a confirmed or probable case of COVID-19
OR
Had close contact^{Footnote 2} with a person with acute respiratory illness who has been to an affected area within 14 days prior to their illness onset
OR
Had laboratory exposure to biological material (e.g. primary clinical specimens, virus culture isolates) known to contain COVID-19.

Factors that raise the index of suspicion^{Footnote 3} should also be considered.

Footnotes

Footnote 1

The incubation period of COVID-19 is unknown. SARS-CoV demonstrated a prolonged incubation period (median 4-5 days; range 2-10 days) compared to other human coronavirus infections (average 2 days; typical range 12 hours to 5 days). The incubation period for MERS-CoV is approximately 5 days (range 2-14 days). Allowing for variability and recall error and to establish consistency with the World Health Organization's COVID-19 case definition, exposure history based on the prior 14 days is recommended at this time.

Return to footnote 1 referrer

Footnote 2

A close contact is defined as a person who provided care for the patient, including healthcare workers, family members or other caregivers, or who had other similar close physical contact or who lived with or otherwise had close prolonged contact with a probable or confirmed case while the case was ill.

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Footnote 3

Other exposure scenarios not specifically mentioned here may arise and may be considered at jurisdictional discretion (e.g. history of being a patient in the same ward or facility during a nosocomial outbreak of COVID-19).

Return to footnote 3 referrer

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.

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