Taipei: The current flu vaccine may provide weaker protection against infection by the new K subclade of the Influenza A virus subtype H3N2, but continues to show clear effectiveness in reducing the risk of severe illness, according to Taiwan's Centers for Disease Control (CDC) on Sunday. The new strain of the flu virus now accounts for nearly 90 percent of confirmed flu cases in Taiwan, the CDC said.

According to Focus Taiwan, CDC spokesperson Tseng Shu-hui stated that Taiwan first detected the K subclade in July, with its share of H3N2 genetic sequences in Taiwan climbing quickly from 30.8 percent in July to 87.7 percent in October. Tseng mentioned findings from the European Centre for Disease Prevention and Control, indicating the K subclade contains multiple genetic mutations and displays major antigenicity differences compared with the 2025-2026 Northern Hemisphere H3N2 vaccine strain.

Tseng further noted that international studies suggest the influenza vaccine maintains strong performance in reducing severe illness and hospitalization risk, despite declining protection against infection. She emphasized the importance of completing flu vaccine doses quickly to reduce health risks, prevent severe cases, and preserve medical capacity as the K subclade continues to spread.

According to Tseng, overall flu outbreak activity in Taiwan is at a low point and showing a steady decline, following the commencement of this year's vaccination drive in October. However, Tseng warned that flu activity could rise again after the New Year period, with the next peak expected around the Lunar New Year.