Health authorities in the UK have issued warnings as a mutated form of the H3N2 influenza virus spreads widely across England this autumn. The variant, known as subclade K (formerly J.2.4.1), has quickly become the dominant strain, according to the latest surveillance by the UK Health Security Agency (UKHSA). Experts are concerned that the virus' rapid evolution could challenge existing immunity and vaccine protection.
Early laboratory analysis shows that subclade K carries at least seven significant genetic changes compared with last season's H3N2 viruses. These mutations affect the virus' surface antigens, potentially reducing the effectiveness of neutralising antibodies from previous infection or immunisation. While early data indicate that the current flu vaccine still offers substantial protection against severe illness, scientists warn that increased transmissibility and lower population immunity could make this season particularly challenging.
