or very high” flu activity as of Wednesday, according to the World Health Organization (WHO).
In six countries – Ireland, Kyrgyzstan, Montenegro, Serbia, Slovenia, and the UK – over 50% of patients with influenza-like symptoms tested positive for the virus. WHO confirmed that a new influenza variant, A (H3N2), now accounts for up to 90% of confirmed cases in the region.
“Just a small genetic variation in the flu virus can place enormous pressure on health systems because people don’t have built-up immunity against it,” said Dr. Hans Kluge, WHO Regional Director for Europe. He stressed the importance of getting vaccinated promptly.
As in previous flu seasons, school-aged children are the primary drivers of community spread, while adults aged 65 and above are at highest risk, often making up the majority of severe cases requiring hospitalization.
WHO had previously warned that a new influenza variant was spreading rapidly but emphasized that vaccination remains the most effective defence.
“The year 2025 has seen the emergence and rapid expansion of a new AH3N2 virus subclade,” said Dr. Wenqing Zhang, Unit Head for Global Respiratory Threats at WHO. The new variant, called J.2.4.1 (subclade K), was first detected in August in Australia and New Zealand and has since spread to over 30 countries.
WHO notes that current data do not indicate increased severity, but the genetic shift represents a notable evolution of the virus. Influenza viruses constantly mutate, which is why vaccine formulations are updated regularly through the Global Influenza Surveillance and Response System (GISRS).
The new variant is not yet included in the latest Northern Hemisphere vaccines, but early evidence suggests that current seasonal vaccines still provide protection against severe disease and reduce hospitalization risk, according to WHO.
Health authorities continue to monitor the situation closely and urge the public, especially vulnerable groups, to get vaccinated and practice preventive measures to curb the spread of the new flu varia
