With the flu starting to spread in Canada, health experts are preparing for a challenging influenza season due to the emergence of an evolving H3N2 strain that may not match this year’s vaccine. Recent federal data revealed that about two percent of nationwide tests returned positive for influenza in the past week. While this falls below the five percent threshold for Canada to declare a seasonal flu epidemic, it represents a noticeable increase from previous weeks.
The ongoing flu season in other parts of the world has seen record numbers of cases in the Southern Hemisphere and an early onset in regions like Asia and the U.K. As Canada enters winter, it could be a precursor to what lies ahead.
Dr. Jesse Papenburg, a pediatric infectious disease specialist, highlighted that the Southern Hemisphere has experienced above-average influenza detections for two consecutive years. Last year, Canada faced one of its worst flu seasons in a decade, and there are concerns that this year could see a similar severity of illness.
Australia recently raised alarm bells with over 410,000 lab-confirmed flu cases, marking the second consecutive record-breaking flu year in the country. Similarly, the U.K. reported a surge in flu cases, three times higher than the previous year, prompting expectations of a prolonged flu season. Parts of Asia, including Japan, have also been hit early by the flu, with schools being closed due to a flu epidemic.
Experts suspect that a mutating H3N2 strain is driving the early flu surge, a type of influenza known for causing severe infections, particularly in older individuals. The concern this year is the widening gap between this virus and the current flu shot.
Dr. Danuta Skowronski, an epidemiology lead, emphasized that the H3N2 strain has started showing significant structural changes as it spreads to northern regions, possibly rendering it mismatched to the latest vaccine formulation.
While Canadian health officials are not making definite predictions, they are closely monitoring global respiratory virus activity. It’s too early to determine the severity of the upcoming flu season in Canada, as various factors like dominant influenza subtype, co-circulation of other viruses, vaccine effectiveness, and coverage will influence the outcome.
Despite uncertainties, experts anticipate a rise in H3N2 cases in Canada, particularly affecting older adults who are more vulnerable to severe flu outcomes. Health authorities urge Canadians to get vaccinated against the flu, emphasizing the importance for seniors. Immunization clinics are already open across several provinces, offering flu shots alongside other seasonal vaccines like COVID-19 and respiratory syncytial virus shots for high-risk groups.
