Following initial alerts across Europe and the US, the Influenza A H3N2 subclade K variant—dubbed 'super flu'—has escalated into one of the most severe early outbreaks in the US and UK. The 2024-25 season marks the worst in the US since 2017-18 and earliest in the UK since 2003-04, with vaccines showing reduced effectiveness against this strain.
The H3N2 subclade K outbreak, previously noted for triggering hospitalizations in Europe, the US, and surveillance in Latin America, has intensified this fall. The US CDC reports the 2024-25 flu season as the most severe since 2017-18, with widespread virus circulation overwhelming health resources.
In the UK, arrivals are the earliest since 2003-04, surprising officials. This 'super flu' strain's rapid spread and vaccine resistance—due to antigenic drift—heighten risks for vulnerable groups.
Health authorities in both nations urge vaccination, hygiene, and early treatment despite challenges. Rising hospitalizations underscore the virus's evolution, complicating preparedness. Ongoing monitoring by CDC, UK bodies, and WHO will track further developments amid global peaks.