Viral shift drives early surge in flu cases
Seasonal influenza is spreading earlier than usual this year, fueled by a highly contagious strain of the H3N2 virus, according to microbiology expert Athanasios Tsakris. Health authorities across the Northern Hemisphere are reporting sharp rises in infections and hospitalizations.
The dominant strain, known as H3N2 subclade K, has triggered a major flu wave three to four weeks ahead of the typical season. Hospitals in the UK recorded record flu-related admissions in December, while New York City reported its highest flu activity in a decade. Greece has also seen an unusually early and strong surge, with elevated flu activity noted even in parts of the Southern Hemisphere.
Experts say the strain’s increased transmissibility is linked to genetic changes that allow it to better evade immune defenses. While there is no evidence of higher mortality, H3N2 infections tend to cause more severe illness in older adults, young children, and people with chronic conditions.
This year’s flu vaccine was developed before subclade K became widespread, meaning protection may be reduced but still offers important defense against severe illness.
