Overview
- CDC-cited reporting says the H3N2 K subclade now makes up a majority of H3N2 cases, with GISAID detections from at least 29 states and Washington, D.C. as of December 4.
- National flu activity remains low but rising per the CDC’s late-November FluView, with H3N2 known to cause more severe illness in older adults and young children.
- Florida has logged more than 1,380 pertussis cases this year, with officials warning of heightened danger for infants and urging vaccination.
- Norovirus positivity reached a record 25% last December and measured 14% the week before Thanksgiving this year, raising concern for holiday outbreaks in crowded venues.
- Experts differ on vaccine matching for K, though UK data suggest the current shot still reduces severe outcomes; the CDC advises vaccination, testing when symptomatic, isolation if positive, masking in crowded indoor spaces, and strict hand hygiene, with on-property AdventHealth resources available to Disney guests.