OSLO, Dec. 17 (Xinhua) -- Influenza is spreading across the World Health Organization (WHO) European Region earlier than usual this winter, with a newly dominant A(H3N2) strain putting added pressure on health systems in some countries, the WHO Regional Office for Europe said on Wednesday.

The agency said the influenza season has started about four weeks earlier than in previous seasons. At least 27 of the 38 countries reporting data are seeing high or very high influenza activity. In Ireland, Kyrgyzstan, Montenegro, Serbia, Slovenia and the United Kingdom, more than half of patients tested for influenza-like illness were positive for influenza.

"The flu comes around every winter, but this year is a little different," said Hans Henri P. Kluge, WHO Regional Director for Europe.

He said a new strain, A(H3N2) subclade K, is driving infections, while noting there is no evidence it causes more severe disease. The WHO said the variant now accounts for up to 90 percent of all confirmed influenza cases in the region.

The WHO said early data from the United Kingdom indicate the current seasonal influenza vaccine reduces the risk of severe health outcomes from A(H3N2), even if vaccination may not prevent infection. It reiterated that vaccination remains the most important preventive step to avoid severe illness, particularly for higher-risk groups such as older people, people with underlying conditions, pregnant women and children. Health workers were also listed as a priority group.

Cases are expected to continue rising until the season peaks, likely in late December or early January, the WHO said, adding that most people will recover on their own, but those with severe symptoms or other medical conditions should seek medical care. ■