Annual influenza reports

FluWatch annual report summary

Surveillance for Canada's 2022–2023 seasonal influenza epidemic began in epidemiological week 35 (week starting August 28, 2022) and ended in epidemiological week 34 (week ending August 26, 2023). The epidemic began in epidemiological week 43 (week ending October 29, 2022) and lasted 10 weeks. Driven by influenza A(H3N2), the epidemic was relatively early, extraordinary in intensity, and short in length. Late-season, Canada saw community circulation of influenza B for the first time since the 2019–2020 season.
A total of 74,344 laboratory-confirmed influenza detections were reported out of 1,188,962 total laboratory tests.

A total of 93% of detections were influenza A (n=68,923).
Influenza A(H3N2) accounted for 89% of the subtyped specimens (n=17,638/19,876).

4,216 influenza-associated hospitalizations were reported by participating provinces and territories.

Most hospitalizations were associated with influenza A (97%), and among hospitalizations with subtype information, 85% (n=1,804) were associated with influenza A(H3N2).
The highest cumulative hospitalization rates were among children aged 0–4 years (131 per 100,000 population) and adults aged 65 years and older (131 per 100,000 population).

The 2022–2023 influenza season in Canada had an extraordinary impact on children and youth.

Nearly half (n=6,194/13,729, 45%) of reported influenza A(H3N2) detections were in the paediatric (younger than 19 years) population.
Weekly paediatric influenza-associated hospital admissions were persistently above historical peak levels for several weeks.
The total number of influenza-associated paediatric hospitalizations (n=1,792) far exceeded historical averages (n=1,091).

Influenza vaccination coverage among all adults for the 2022–2023 influenza season (43%) was slightly higher than the previous season (39%). Among those at higher risk of complications from influenza (adults aged 65 years and older and adults aged 18–64 years with chronic medical conditions), vaccination coverage was 74% and 43% respectively, both similar to the previous season and below Canada's influenza vaccination coverage goal of 80% for those at higher risk.
With the return of seasonal influenza circulation and endemic co-circulation of multiple high burden respiratory viruses, sustained vigilance is warranted. Annual seasonal influenza vaccination is a key public health intervention available to protect Canadians.