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Overview
- In a Dec. 11 alert, PAHO urged countries in the Americas to prepare for a potentially earlier or more intense 2026 influenza season based on WHO surveillance showing rising global H3N2 activity.
- Mexico confirmed the region’s first H3N2 subclade K case on Dec. 12, with authorities reporting the patient recovered after standard antiviral treatment.
- WHO and PAHO report no clear signal of increased clinical severity so far, though H3N2‑dominant seasons historically burden older adults and other high‑risk groups.
- North America is currently the most affected subregion for H3N2 this year, with the United States, Canada and Mexico recording the highest case counts, while the UK has seen rising hospitalizations and some school closures linked to subclade K.
- Health agencies recommend reinforced surveillance for influenza, RSV and SARS‑CoV‑2, prioritized vaccination of high‑risk groups, and securing antivirals and PPE, with preliminary data indicating meaningful protection against severe disease even without a perfect vaccine match.