With the increase in flu cases in Canada, health experts are preparing for a challenging influenza season due to the global spread of a mutating H3N2 strain. This strain may not match this year’s flu vaccine. Recent federal data indicates around two percent of nationwide tests returned positive for influenza in the previous week, showing a rise from preceding weeks but still below the threshold for declaring a seasonal flu epidemic in Canada.
The ongoing flu season has seen record case numbers in the Southern Hemisphere and an early onset in parts of Asia and the U.K. This trend could be indicative of what Canada might face in the upcoming winter months. Dr. Jesse Papenburg, a pediatric infectious disease specialist, noted that for the second consecutive year, the Southern Hemisphere has experienced higher-than-average influenza detections, hinting at a potentially severe flu season in Canada.
In Australia, healthcare professionals have raised concerns following over 410,000 lab-confirmed flu cases, the second consecutive year of record-high flu activity. The U.K. also reported an early flu season, with cases three times higher than the previous year, forecasting an extended flu season. In Asia, notably Japan, an early flu outbreak led to school closures, with experts attributing it to a mutating H3N2 strain known for severe infections, especially in older individuals.
Dr. Danuta Skowronski, an epidemiology lead, is monitoring these mutations closely, particularly the structural changes seen in the H3N2 strain as it spreads to northern regions. This mutation could render the current vaccine mismatched to the evolving virus. The flu shot for this season targets two influenza A strains, including various subtypes of H1N1 and H3N2, along with an influenza B strain.
Canadian health officials are cautious in making predictions at this stage. While monitoring global respiratory virus activity, including data from the Southern Hemisphere, the Public Health Agency of Canada emphasized that it is premature to determine the severity of the upcoming flu season in Canada. Factors such as dominant influenza subtype, vaccine effectiveness, and coverage will influence the season’s outcome.
Although early data in Canada indicates an equal distribution of H1N1 and H3N2 flu subtypes, experts anticipate a rise in H3N2 cases. Typically, H3N2 seasons are considered the most severe, particularly affecting adults aged 60 and above, leading to increased hospitalizations and fatalities. While this year’s vaccine may not be a perfect match for the dominant H3N2 strain, health experts recommend getting vaccinated, especially for the elderly population.
Seasonal flu vaccination clinics are operational across several provinces, urging Canadians to consider getting flu shots alongside other seasonal vaccines like COVID-19 vaccines. Despite some regions requiring out-of-pocket payments for vaccines, officials stress the importance of vaccination to protect high-risk groups from serious illnesses, such as respiratory syncytial virus shots for elderly adults and newborns.