Flu variant is driving a surge of cases across Canada and the US.

The Weather Network reports a new flu subvariant (reported as subclade K) is linked to rising cases across Canada and the United States, and experts say this season's vaccine was not a close match but still appears to provide some protection.

The Weather Network reports a new flu variant is driving a rise in cases across Canada and the United States. The circulating virus is reported as subclade K. Flu season in North America typically peaks from December through February. Authorities and clinicians note that the strains selected for the 2025–2026 vaccine were not a close match to subclade K, but evidence suggests the vaccine still provides protection. Key facts: - A new flu subvariant (reported as subclade K) is being reported as responsible for increased case counts across Canada and the US. - Flu season generally peaks December through February in North America, which coincides with the current rise in cases. - Officials and clinicians report the 2025–2026 vaccine strains were not an ideal match for subclade K, while evidence indicates the vaccine still offers some protection. - The article reports that home testing for flu is often not considered especially useful, and that antiviral medicines such as oseltamivir (Tamiflu) have limited effectiveness and known side effects, with many emergency department clinicians rarely recommending them. Summary: The emergence of subclade K is associated with rising case counts during the region's typical flu peak, and clinicians are reporting a partial vaccine match rather than a close match. Undetermined at this time.