Overview
- EU surveillance shows influenza detections rising three to four weeks earlier than in recent seasons, with A(H3N2) subclade K driving the uptick.
- The emerging subclade carries multiple hemagglutinin mutations that laboratory and epidemiological signals suggest may increase transmissibility.
- ECDC and GISAID data indicate subclade K now represents about one third of recent A(H3N2) sequences globally and nearly half in the EU.
- Authorities urge older adults, pregnant people, those with chronic conditions, immunocompromised individuals, and health and long‑term care workers to get vaccinated now, noting immunity takes roughly two weeks and early UK data show protection against severe outcomes.
- Regions are stepping up measures, with Catalonia forecasting a mid‑December peak and reporting coverage gaps, and Asturias advising masks for symptomatic people indoors and extending evening walk‑in vaccination.