Canadian respiratory virus surveillance report (CRVSR): About this report

Change in reporting location

A weekly overview of respiratory virus data submitted by laboratories across Canada is available below. Previous summaries of weekly respiratory virus laboratory data collected by the Respiratory Viruses Detection Surveillance System (RVDSS) are available on the archived reports page.

On this page

• Introduction
• Archived surveillance reports
• General interpretation notes
• Data sources and coverage
• Surveillance definitions and indicators
• Data stream-specific technical notes
• Provincial, territorial, and international report links

Introduction

The Canadian respiratory virus surveillance report, produced by the FluWatch+ surveillance program, offers a weekly overview of key trends in respiratory viruses, such as influenza (flu), COVID-19, and respiratory syncytial virus (RSV) in Canada.

The FluWatch+ surveillance system receives surveillance data from multiple sources and is made possible through the collaboration of numerous partners across Canada. To learn more about the FluWatch+ surveillance system see the Overview of respiratory monitoring in Canada page.

Each tab in this report contains different information. The "Snapshot" tab contains high level combined trends for COVID-19, influenza, RSV, and other seasonal respiratory viruses. More detailed trends on COVID-19, influenza and RSV can be found on the individual virus tabs. The “Explore the data” tab allows users to download weekly surveillance datasets and choose different views of the data not found in the existing tabs.

Archived surveillance reports

Older versions of this report and previous epidemiological summaries of respiratory viruses are available on the archived reports page.

For a summary of what occurred during a particular surveillance period, please refer to the report for week 34 on the archived reports page or for a more in-depth analysis, refer to the annual reports page.

Surveillance reports for influenza from 2010 to 2023 can be found in the Government of Canada Publications Archives by searching "FluWatch".

Respiratory virus surveillance data

Download the national dataset from the Explore the data tab.

National respiratory virus data are also available within text description links found under the figures in the Canadian respiratory virus surveillance report.

Historical downloadable national influenza datasets can also be found in the Government of Canada Open Data Portal.

Surveillance data for individual provinces and territories must be obtained through the respective province or territory.

General interpretation notes

• Surveillance data reported in the Canadian Respiratory Virus Surveillance Report is used to monitor trends in respiratory virus activity throughout the surveillance period. This includes where and when viruses are circulating, which viruses are present, who is most affected and whether activity is increasing or decreasing. These data are an underestimate and are not intended to reflect the true number of cases of respiratory virus diseases in Canada.
• Due to variations in how data are reported, indicators for COVID-19, influenza and RSV may not be directly comparable. Where data for each virus are presented separately, comparisons between the viruses should be made with caution.
• The data in the Canadian Respiratory Virus Surveillance Report represent surveillance data that are available at the time of writing. Surveillance partners are encouraged to update previously submitted data throughout the surveillance period. All data are preliminary and may change as more reports are received throughout the surveillance period.
• The FluWatch+ program refers to time in surveillance weeks. This allows for the comparison of historical data (e.g. comparing data from week 45 in the 2021-22 period to week 45 of the 2019-2020 period). Data are aggregated by surveillance weeks that run from Sunday to Saturday.
• The surveillance period begins in week 35 of a calendar year (end of August) and ends in week 34 of the following calendar year (end of August). A calendar of surveillance weeks for the current period is available online for reference.
• What do the arrows mean? The arrows (up, down, or stable) show the overall trend for each surveillance indicator. These trends are based on a weekly data, averaged over 4 weeks to smooth out short-term changes/variation (4 week rolling average). The value that defines a change in trend varies depending on the indicator.
  • Laboratory data:
    • Most respiratory viruses: If the percentage of positive tests changes by 0.5% or more from the previous week, the arrow will show an increase or decrease; otherwise a stable trend is assigned.
    • Adenovirus and entero/rhinovirus only: If the percentage of positive tests changes by 1% or more from the previous week, the arrow will show an increase or decrease; otherwise a stable trend is assigned.
  • Hospitalizations: If the rate of positive tests changes by 5% or more from the previous week, the arrow will show an increase or decrease; otherwise a stable trend is assigned.
  • Outbreaks: If the number of outbreaks changes by 5% or more from the previous week, the arrow will show an increase or decrease; otherwise a stable trend is assigned.
  • FluWatchers: If the percentage of participants reporting cough and fever changes by 0.1% or more, the arrow will show an increase or decrease; otherwise a stable trend is assigned.

Data sources and coverage

Data stream	Data source	Coverage (Number of participating provinces and territories)
Aggregate laboratory confirmed detections	Data are collected through the Respiratory Virus Detection Surveillance System (RVDSS). RVDSS is a sentinel laboratory surveillance system consisting of a network of 20 laboratories (includes provincial, territorial, regional and hospital laboratories). There are reporting laboratories in all provinces and territories (PTs) but not all respiratory virus testing in Canada is captured through RVDSS. Laboratories report aggregate data for up to 8 respiratory viruses: SARS-CoV-2 (the virus that causes COVID-19) Influenza (commonly referred to as the flu) Respiratory syncytial virus (RSV) Human parainfluenza virus Adenovirus Human metapneumovirus Enterovirus/rhinovirus Human coronavirus 229E/OC43/NL63/HKU1 (does not include SARS-CoV-2)	COVID-19, Influenza and RSV: 13 out of 13 PTs
Case-level laboratory detections	Some of the RVDSS provincial, territorial and regional public health laboratories provide age information for COVID-19, influenza and RSV detections.	COVID-19: 12 out of 13 PTs, representing approximately 99% of the population in Canada Influenza: 13 out of 13 PTs, representing 100% of the population in Canada RSV: 12 out of 13 PTs, representing approximately 99% of the population in Canada
Genetic and antigenic characterization of SARS-CoV-2 and influenza, including antiviral resistance	The National Microbiology Laboratory Branch (NMLB) provides data on the genetic and antigenic characterization of SARS-CoV-2 and influenza isolates, as well as their susceptibility to antiviral agents. NML receives a proportion of positive isolates from participating provinces and territories.	Not applicable.
COVID-19 and influenza activity levels	Provincial and territorial ministries of health report on the level of activity associated with COVID-19 or influenza in their jurisdiction using methods developed in collaboration with PHAC.	COVID-19: 9 out of 13 PTs Influenza: 12 out of 13 PTs
FluWatchers	Volunteer participants in all provinces and territories	There are volunteers reporting from all PTs across Canada. Further information on number of participants reporting per week by PT can be found in the FluWatchers report.
Outbreaks	Outbreaks of test-confirmed COVID-19, influenza and RSV in high-risk settings are reported from varying provincial and territorial ministries of health.	COVID-19: 11 out of 13 PTs, representing 97% of the Canadian population Influenza: 11 out of 13 PTs, representing 97% of the Canadian population RSV: 9 out of 13 PTs, representing 79% of the Canadian population
PTSOS (Provincial and Territorial Severe Outcome Surveillance)	Hospitalizations, ICU admissions and deaths associated with COVID-19, influenza (influenza type/subtype), or RSV by age or age group are reported by varying provincial/territorial ministries of health, depending on the virus.	COVID-19: 10 out of 13 PTs, representing approximately 83% of the population in Canada, provide hospitalization data for COVID-19; of these PTs, 9 out of 10 provide hospitalization age data, representing approximately 44% of the population. 8 out of 13 PTs, representing approximately 22% of the population in Canada, provide ICU data for COVID-19. All 8 out of 8 PTs provide age data. 10 out of 13 PTs, representing approximately 83% of the population in Canada, provide death data for COVID-19. All 10 out of 10 PTs provide age data. Influenza: 10 out of 13 PTs, representing approximately 83% of the population in Canada, provide data for influenza-associated hospitalizations; 8 out of 10 PTs, representing approximately 22% of the population in Canada, provide hospitalization data for influenza with age information. 8 out of 13 PTs, representing approximately 22% of the population in Canada, provide data for influenza-associated ICU admissions. All 8 out of 8 PTs provide age data. 8 out of 13 PTs, representing approximately 22% of the population in Canada, provide data for influenza-associated deaths. All 8 out of 8 PTs provide age data. RSV: 7 out of 13 PTs, representing approximately 56% of the population in Canada, provide data for RSV-associated hospitalizations; of these PTs, 6 out of 7 provide hospitalization age data, representing 15% of the population in Canada. 6 out of 13 PTs, representing approximately 17% of the population in Canada, provide data for RSV-associated ICU admissions. All 6 out of 6 PTs provide age data. 6 out of 13 PTs, representing approximately 17% of the population in Canada, provide data for RSV-associated deaths. All 6 out of 6 PTs provide age data.
Pediatric severe outcomes	The SPRINT-KIDS sentinel pediatric (≤18 years) hospital network provides severe outcome monitoring in both the emergency department and inpatient facilities across Canada for COVID-19, influenza and RSV. This network reports detailed case-level information on pediatric hospitalizations, ICU admissions and deaths attributable to COVID-19, influenza or RSV.	15 pediatric hospitals across 8 provinces in Canada (all provinces except New Brunswick and Prince Edward Island).

Surveillance definitions and indicators

Data stream	Definitions	Indicators	Indicator calculations
Laboratory detections (includes aggregate and case-level)	SARS-CoV-2 detection: Identification of SARS-CoV-2 through a positive test result from laboratory-based nucleic acid amplification tests (NAAT), point-of-care NAAT or antigen tests, or by evidence of infection demonstrated by viral-specific antibodies, seroconversion, or a significant rise in viral-specific antibody titers. Influenza detection: Identification of influenza virus through a positive result from viral culture, immunoassay, or nucleic acid amplification tests (NAAT). RSV detection: Identification of respiratory syncytial virus (RSV) through a positive result from polymerase chain reaction (PCR), direct fluorescent antibody (DFA) assay, or tissue culture.	Aggregate: Number of detections by week by virus Percentage of laboratory tests positive by week by virus	Numerator: weekly number of virus detections Denominator: total weekly number of specimen tested
		Case-level: Cumulative and weekly number of SARS-CoV-2, influenza and RSV detection by age group, type and subtype (where applicable)	Not applicable
Genetic and antigenic characterization of SARS-CoV-2 and influenza, including antiviral resistance	SARS-CoV-2 variant: All viruses change over time, including SARS-CoV-2, the virus that causes COVID-19 disease. These changes are called mutations and viruses with mutations are called variants.	Not applicable	Not applicable
COVID-19 activity levels	Threshold definitions for assessment of COVID-19 activity levels Weekly percent positivity: No activity = 0% Low activity= <5% Moderate activity = 5-14.9% High activity = 15-24.9% Very high activity = ≥25% LTCF outbreaks per 100,000: Large population (> 1,000,000) No activity = 0 Low activity = <2 Moderate activity = 2-3 High activity = 4-5 Very high activity = >5 Medium Population (100,000 – 1,000,000) No activity = 0 Low activity = <10 Moderate activity = 10-15 High activity = 16-20 Very high activity = >20 Small Population (<100,000) No activity = 0 Low activity = N/A Moderate activity = <25 High activity = 25-50 Very high activity = >50	Geographic spread, intensity and trajectory of COVID-19 transmission	Assessment process: COVID-19 activity levels are derived based on: Weekly percent positivity Weekly LTCF outbreaks per 1,000,000 population Trajectory of wastewater viral activity (where available) The overall activity levels are based on two indicators where available: percent positivity and LTCF outbreaks per 1,000,000 population for the most recent epi week. Each indicator is assigned a level ranging from ‘no activity detected’ (level 0) to ‘very high activity’ (level 4), based on established thresholds Overall activity level is then determined using the average level of the available indicators (rounding to the nearest whole number). The overall trajectories (increasing, decreasing or no change) are based on the change from the previous week and are based on the following indicators where available: percent positivity, LTCF outbreaks per 1,000,000 population, and wastewater trajectory for the most recent epi week. The overall trajectory is then determined by the mode of available trajectories.
Influenza activity level	No activity: No laboratory-confirmed influenza detections in the reporting week; however, sporadically occurring ILI may be reported. Sporadic: Sporadically occurring ILI and laboratory-confirmed influenza detection(s) with no outbreaks detected within the influenza surveillance region. Localized: Evidence of increased ILI and laboratory-confirmed influenza detection(s) and outbreaks in facilities under surveillance occurring in less than 50% of the influenza surveillance region. Widespread: Evidence of increased ILI and laboratory-confirmed influenza detection(s) and outbreaks in facilities under surveillance occurring in greater than or equal to 50% of the influenza surveillance region.	Geographic spread and intensity of influenza transmission.	Not applicable
FluWatchers	Not applicable	Weekly percentage of FluWatchers participants reporting cough and fever.	Numerator: weekly number of participants reporting cough and fever. Denominator: total weekly participants reporting.
Outbreaks	Outbreak settings: Long-term care settings: Facilities that provide living accommodation for people who require on-site delivery of 24 hour, 7 days a week supervised care, including professional health services, personal care and services such as meals, laundry and housekeeping or other residential care facilities. Acute care facilities: Publicly funded facilities providing medical and/or surgical treatment and acute nursing care for sick or injured people, through inpatient services. (i.e. hospitals including inpatient rehabilitation and mental facilities). Retirement facilities: A residential complex, or part of a residential complex that is: occupied primarily by persons who are 65 years of age or older, occupied by at least six persons not related to the operator, AND where the operator makes at least two care services available to residents. The residential complex provides accommodation, meals, housekeeping, linen and recreational services for residents that are able to move independently or with the assistance of one other person. Residents are medically and physically stable, who may be living with physical disability, mental health diagnoses, or mild dementia. Example facilities: retirement homes retirement residences senior living facilities designated supported living facilities (occupied primarily by persons who are 65 years of age or older). Remote and/or isolated communities: A community that is physically and/or socially separated from the surrounding population. For example, communities that are geographically isolated due to limited transportation links. Other settings: Any other locations/facilities not previously identified in which an outbreak of the influenza or ILI occurs. Example facilities: assisted living or hospice settings private hospitals/clinics correctional facilities colleges/universities schools/daycares adult education centres shelters workplaces supported living facilities/supportive housing/assisted living facilities for individuals with disabilities group homes residential treatment centres Outbreak definitions: For long-term care, acute care, and retirement facilities: Laboratory-confirmed influenza or RSV outbreak: Two or more cases of ILI within 7 days, and at least 1 laboratory-confirmed case of influenza or RSV in the same setting (on the same floor, or in the same unity or ward). Test-confirmed COVID-19 outbreak: Two or more test-confirmed cases of COVID-19 which are epidemiologically linked to a specific setting or location. Test-confirmed cases include positive COVID-19 results from nucleic acid amplification tests (NAAT) or rapid antigen tests (RAT). For remote and/or isolated communities and other settings: Laboratory-confirmed influenza or RSV outbreak: Unusual or unexpected number of ILI cases within 7 days and at least 1 laboratory-confirmed case of influenza or RSV. Test-confirmed COVID-19 outbreak: Two or more test-confirmed cases of COVID-19 which are epidemiologically linked to a specific setting or location. Test-confirmed cases include positive COVID-19 results from nucleic acid amplification tests (NAAT) or rapid antigen tests (RAT).	Cumulative and weekly number of test-confirmed outbreaks by setting.	Not applicable
PTSOS (Provincial and Territorial Severe Outcome Surveillance)	Hospitalizations: Any person admitted to hospital with laboratory-confirmed COVID-19, influenza, or RSV. ICU admissions: Any person with laboratory-confirmed COVID-19, influenza, or RSV admitted to an intensive care unit (ICU) or requiring mechanical ventilation. Deaths: A death occurring in any person with laboratory-confirmed COVID-19, influenza, or RSV with no period of complete recovery between illness and death.	Weekly and cumulative COVID-19, influenza or RSV associated hospitalization rates per 100,000 population.	Numerator: number of COVID-19, influenza, or RSV associated hospitalizations Denominator: sum of population of reporting provinces and territories
Pediatric severe outcomes	Hospitalizations COVID-19:Admissions attributable to acute COVID-19 or resulting complication with detection of SARS-CoV-2 by laboratory-based NAAT, viral specific antibodies, demonstrated seroconversion or diagnostic rise in viral specific antibody titre, or point of care NAAT or antigen test. Influenza:Admissions attributable to influenza infection or a complication of infection (i.e. admitted for influenza or complication of influenza such as febrile convulsion, pneumonia), with laboratory confirmation of influenza by positive culture, positive immunoassay or NAAT. RSV:Admissions attributable to an RSV infection or a complication of infection (i.e. admitted for RSV or complication of RSV such as pneumonia), with laboratory confirmation of RSV by a specific laboratory test, such as PCR, DFA or tissue culture. ICU admissions Any individual meeting the hospitalization definition that was admitted to an intensive care unit (ICU). Deaths Any individual meeting the hospitalization definition that has died in-hospital. Coinfections Hospitalizations and ICU admissions where two or more viruses (among COVID-19, influenza, or RSV) were laboratory confirmed.	Cumulative and weekly number of pediatric hospitalizations, ICU admissions and deaths by age group.	Not applicable

Data stream-specific technical notes

Data stream	Technical notes
Laboratory detections (includes aggregate and case-level data)	Most laboratory tests are conducted on: acute respiratory infection cases at emergency departments hospitalized severe acute respiratory virus infection cases outbreak cases Outpatient cases with symptoms of respiratory virus infection may be targeted, but testing is typically limited to people at higher risk for severe outcomes. Testing for RSV and other respiratory viruses has been influenced by the COVID-19 pandemic. Changes in laboratory testing practices may affect the comparability of data to previous seasons. Case-level data represents a portion of laboratory-confirmed detections for all viruses. Respiratory testing algorithms vary by province and territory.
Genetic and antigenic characterization of SARS-CoV-2	Changes in circulating SARS-CoV-2 viruses are monitored by genetic sequencing and modelling. It takes time to collect, sequence and process viral genomes, so there is often a period of 2 to 3 weeks where data are still being processed. A nowcasting model is used to estimate the current variant proportions for this period. Nowcasting uses statistical models to estimate the current situation based on earlier trends. It provides estimates for the most recent weeks when the data is still accumulating and is therefore incomplete. For more detailed information about how nowcasting works, refer to Nowcasting methods.
COVID-19 and influenza activity levels	Activity level definitions and methods of assessment may not be uniformly applied across all regions and provinces and territories but serve as a rough operational definition to enable comparability of levels across jurisdictions in Canada. Methods for deriving activity levels for COVID-19 and influenza are different and are not comparable to each other.
FluWatchers	Not applicable
Outbreaks	Due to data collection practices in some provinces and territories, some outbreaks cannot be confirmed to be due to a specific virus; thus, the terms “associated with” or “detected” are used when reporting outbreaks nationally. Not all provinces and territories provide outbreak data for all viruses. Read more in the data source and coverage section. Not all provinces and territories conduct surveillance in all facility types Not all jurisdictions within a province or territory report outbreaks. Outbreak definitions and facility types may not be uniformly applied across all regions/provinces and territories but serve as a rough operational definition across jurisdictions in Canada.
PTSOS (Provincial and Territorial Severe Outcome Surveillance)	Not all provinces and territories provide severe outcomes data for all viruses. Read more in the data source and coverage section.
Pediatric severe outcomes	Not applicable

Provincial, territorial, and international report links