Revision History

The CDC reported that the 2025-2026 flu vaccine was only 25-35% effective in adults — one of the worst performances in over a decade — after a mutant H3N2 variant called subclade K emerged too late to be included in the vaccine formulation. With at least 27 million illnesses, 350,000 hospitalizations, and 22,000 deaths so far this season, the poor vaccine match coincided with the Trump administration's controversial decision to drop routine flu shot recommendations for children, raising urgent questions about America's influenza preparedness infrastructure.