Overview
- ECDC reports the strain has been detected on all continents and accounts for about one-third of global H3N2 sequences since May, nearing half in the European Union.
- CDC data show roughly 50% of H3N2 lab-confirmed cases in the United States are subclade K.
- New York State lab-confirmed flu cases rose from 3,979 on Nov. 1 to 9,858 on Nov. 15, with sharp increases in Nassau and Suffolk counties.
- A UKHSA preprint finds vaccine effectiveness of about 70–75% against hospitalization in children and 30–40% in adults as subclade K dominates early in England.
- Vaccination uptake has fallen, including a drop in U.S. child coverage from 62% in 2019–20 to 49% in 2024–25, and public-health agencies warn a larger epidemic could strain healthcare services.