Experts Warn of an Unusually Early and Severe Flu Season

This year’s flu season has arrived more than a month early, driven by a mutated H3N2 influenza strain that emerged unexpectedly in the summer. Scientists say the virus’s seven new mutations may help it evade existing immunity, allowing it to spread faster—reflected in a higher estimated R number of 1.4, compared to the usual 1.2.

Experts from the Francis Crick Institute and University of Oxford warn this could be the worst flu season in a decade, with greater severity, especially among older adults. While the seasonal flu vaccine offers partial protection, it remains the best defence, reducing illness severity and hospitalisations.

The NHS has issued a “flu jab SOS”, urging people to get vaccinated immediately. Though uncertainty remains, the early and aggressive spread of this “nastier” H3N2 variant signals a challenging winter ahead for health systems and vulnerable populations.

12-11-2025