Overview
- CDC data indicate about 89% of H3N2 samples since late September are the K subclade, making it the dominant strain.
- U.S. estimates for the season include at least 4.6 million illnesses, 49,000 hospitalizations, and 1,900 deaths, according to the CDC.
- New York City logged its busiest week of flu-related ER visits in a decade in late December, with Manhattan cases up 104% in mid-December.
- Genetic drift has reduced vaccine match for infection prevention, yet clinicians report vaccination still helps prevent hospitalization and severe outcomes.
- Experts see no clear sign the strain is inherently more severe than other H3N2 viruses, and early antivirals—oseltamivir, zanamivir, baloxavir, and peramivir—remain recommended.