Canadian respiratory virus surveillance report: Influenza

Update schedule: This page was last updated on September 27th, 2024, 10am ET, with data up to and including ... (surveillance week ...).

Influenza highlights  for the week ending (week )

Influenza and influenza-like illness activity: Geographic spread

Figure 1: Map of influenza/ILI activity by reporting region in Canada, week (week ending )

Hover over the map below to learn more about the current influenza and ILI activity levels in each of Canada's health regions. To get a closer look at the regions, scroll while hovering over the map to zoom in or out. Click on a specific region to highlight and focus on it, and click on it again to zoom out to the default view.

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Figure 1: Data notes

The flu activity map reflects only a single FluWatch+ indicator and is based on specific definitions. Provincial and territorial partners may choose to apply these definitions where appropriate. This map is not reflective of who is and is not reporting surveillance indicators contained in the report.

For more information on the definitions, provincial and territorial coverage of each surveillance indicator or links to Provincial and territorial reports, please consult the About this report tab.

Laboratory-confirmed detections

Figure 2: Number of reported influenza detections and percentage of tests positive in Canada, by type, subtype, and report week

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Figure 3: Percentage of tests positive for influenza in Canada for surveillance period 2025-2026 compared to previous periods

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Figure 3: Data notes

The epidemic threshold is 5% tests positive for influenza. When it is exceeded, and a minimum of 15 weekly influenza detections are reported, a seasonal influenza epidemic is declared.

Figure 4: Number of detections in Canada, by age group and report week

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Figure 5: Proportion of influenza detections in Canada for season 2025-2026 by and by age group

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Influenza strain characterization

Each year, the composition of the influenza vaccine is selected far in advance of the season. In February 2025, the World Health Organization recommended the following strains for the 2025-2026 northern hemisphere influenza vaccine:

Component	Vaccine type	Vaccine strains or reference viruses	Genetic clade (subclade)
A(H3N2)	Egg-based	A/Croatia/10136RV/2023 (H3N2)-like virus or	2a.3a.1(J.2)
	Cell-based, recombinant protein-based, and nucleic acid-base	A/District of Columbia/27/2023 (H3N2)-like virus
A(H1N1)	Egg-based	A/Victoria/4897/2022 (H1N1)pdm09-like virus or	5a.2a.1(C1.1)
	Cell-based, recombinant protein-based, and nucleic acid-base	A/Wisconsin/67/2022 (H1N1)pdm09-like virus
B	Egg-based, cell-based, recombinant protein-based, and nucleic acid-base	B/Austria/1359417/2021 (B/Victoria lineage)-like virus	3a.2(C)

Note: Bolded strains represent the reference viruses used for hemagglutination inhibition (HI) assays by the National Microbiology Laboratory Branch

Throughout the 2025-2026 season, influenza specimens from across Canada are sent to the National Microbiology Laboratory Branch (NMLB) for antigenic and genetic characterization.

Specimens are antigenically characterized to monitor changes in circulating influenza viruses. Antigenic characterization results show how similar the circulating viruses are to vaccine reference viruses through HI assays that use antisera raised against reference viruses.

Genetic characterization is also performed to determine the clade and subclade of circulating influenza viruses for comparison of gene sequence similarity to the vaccine strains.

It is important to view antigenic and genetic characterization data together because influenza clades and subclades can differ genetically but remain antigenically similar.

Antigenic characterization

Table 1: Results of antigenic characterization, by hemagglutination inhibition assay comparing circulating influenza isolates to their respective vaccine reference viruses in Canada, 2025-2026 season.

Note: A Circulating viruses are considered to have similar reactivity with an <8-fold HI titre reduction compared to the vaccine reference virus and reduced reactivity with an ≥8-fold HI titre reduction.

Genetic characterization

Table 2: Genetic characterization results of influenza A(H1N1), influenza A(H3N2), and influenza B in Canada, 2025-2026 season

Antiviral resistance

The National Microbiology Laboratory Branch (NMLB) also assesses the antiviral resistance of influenza viruses received from Canadian laboratories.

Table 3: Antiviral resistance results of influenza A(H1N1), influenza A(H3N2), and influenza B in Canada, 2025-2026 season

Outbreaks

Figure 6: Number of laboratory-confirmed outbreaks in Canada associated with influenza, by setting and report week, 2025-2026 surveillance period

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Severe outcomes

Provincial and territorial hospitalizations

Among reporting provinces and territories, some do not provide data on all severe outcomes (hospitalizations, ICU admissions, and deaths) and some do not provide age data. For additional information about the current reporting situation, please refer to the data sources and coverage section in the About this report tab.

Figure 7: Number and crude rate of laboratory-confirmed influenza-associated hospitalizations in Canada (from participating provinces and territories) by report week, 2025-2026 surveillance period

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Figure 8: of influenza-associated hospitalizations by age group and by surveillance week, Canada, participating provinces and territories, 2025-2026 surveillance period

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Sentinel hospitalizations (pediatrics)

Pediatric (less than 18 years of age) COVID-19, influenza, and RSV-associated severe outcomes data are reported by the Surveillance Program for Rapid Identification and Tracking of Infectious Diseases in kids (SPRINT-KIDS).

Figure 9: Number of pediatric laboratory-confirmed influenza hospitalizations, by influenza type, by report week, reported by SPRINT-KIDS, 2025-2026 surveillance period

• *: Preliminary data are shaded in grey.

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Figure 10: Proportion of pediatric laboratory-confirmed influenza hospitalizations by age group, reported by SPRINT-KIDS, 2025-2026 surveillance period

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Influenza vaccine monitoring

Vaccine monitoring refers to activities related to the monitoring of influenza vaccine coverage and vaccine effectiveness.

Vaccine coverage

Influenza vaccine coverage estimates for the 2025-2026 surveillance period are anticipated to be available in March 2026.

Vaccine effectiveness

Influenza vaccine effectiveness estimates for the 2025-2026 surveillance period are anticipated to be available in February or March 2026.