Weekly influenza reports

February 26, 2023 to March 4, 2023 (week 9)

• At the national level, influenza activity remains low at levels typically seen in late spring/early summer. Influenza activity continues to be reported in almost all provinces.

Virologic

• In week 9, the percentage of tests positive for influenza was 1.3% and a total of 326 laboratory detections (173 influenza B and 153 influenza A) were reported. Influenza A and B are circulating at similar levels.
• Among subtyped influenza A detections in week 9, 63% (25) were influenza A(H1N1).

Syndromic

• The percentage of visits for influenza-like illness (ILI) was 0.7% in week 9. The percentage visits for ILI is below levels typical of this time of year.
• The percentage of FluWatchers reporting fever and cough was 1.4% in week 9, below levels typical of this time of year.

Outbreaks

• From August 28, 2022 to March 4, 2023 (weeks 35 to 9), 606 laboratory-confirmed influenza outbreaks have been reported (two new laboratory-confirmed influenza outbreaks were reported in week 9).

Severe Outcomes

• The highest cumulative hospitalization rate up to week 9 is among adults 65 years of age and older (131/100,000 population) and children under 5 years of age (121/100,000 population). The overall cumulative hospitalization rate this season to date is 47/100,000 population.

Other Notes

• The World Health Organization has released its recommended composition of the northern hemisphere influenza vaccine for use in the upcoming 2023-2024 season. The recommended strains were changed for the A(H1N1) component compared to the current 2022-2023 northern hemisphere vaccine.