[National Bureau of Disease Control and Prevention releases popular science questions and answers on influenza vaccination] On September 7, the National Administration of Disease Control and Prevention released popular science questions and answers on influenza vaccination. Currently, seasonal epidemics are mainly caused by the H1N1 and H3N2 subtypes of influenza A virus and the Victoria strain of influenza B virus. The dominant strains vary in different epidemic seasons. Even within the same epidemic season, different types and subtypes of influenza viruses may alternately become dominant strains. Since the influenza virus mutates frequently, and the level of protective antibodies produced after vaccination gradually attenuates over time, the protective effect of the influenza vaccine generally lasts for 6 to 8 months, so the influenza vaccine needs to be vaccinated every year. Compared with the previous year, all three vaccine components have been updated this year. The components of the trivalent influenza vaccine produced in chicken embryos in the northern hemisphere recommended by the World Health Organization from 2026 to 2027 are: A/Missouri/11/2025 (H1N1)pdm09-like virus; A/Darwin/1454/2025 (H3N2)-like virus; B/Tokyo/EIS13-175/2025 (B/Victoria lineage)-like virus.