A newly mutated strain of the H3N2 influenza virus is spreading rapidly across continents, prompting global health experts to issue warnings about a potentially severe flu season. The variant, first linked to outbreaks in Japan and the United Kingdom, has now been detected worldwide. Scientists attribute the surge partly to reduced population immunity, as people have had limited exposure to flu viruses in recent years.

Researchers at Cambridge University and the Francis Crick Institute report that the H3N2 'subclade K' strain carries seven new mutations, making it antigenically distinct from previous forms. Although symptoms may not be more severe than typical flu, experts caution that lower immunity could lead to higher infection rates and hospitalizations, particularly among the elderly and vulnerable. Current flu vaccines may offer only partial protection, though health authorities stress that some immunity is better than none.

Public health agencies in the UK and Japan have urged vaccination, hygiene measures, and temporary school closures to curb transmission. Experts warn that this season’s mismatch between circulating strains and vaccines could test global preparedness for respiratory outbreaks.