Core Viewpoint - The article highlights the rising flu activity in southern China, with predictions of an earlier flu season this year compared to last, primarily driven by the different circulating strain, H3N2, which the public has lower immunity against [2][3]. Group 1: Flu Activity and Strain Information - The current flu season is characterized by the predominance of the H3N2 strain, contrasting with last year's H1N1 strain, indicating a need for heightened awareness due to lower public immunity [3]. - Clinical symptoms of H3N2 include high fever, cough, sore throat, body aches, fatigue, and headache, which are similar to other flu strains [3]. Group 2: Vaccination Recommendations - Vaccination is emphasized as the most effective method to prevent flu and reduce severe cases, with the recommended vaccination period being from September to November to ensure immunity before peak season [5]. - Annual vaccination is necessary due to the rapid mutation of flu viruses, which may differ from year to year, thus requiring updated protection [6]. - High-risk groups, including children under 5, the elderly over 65, pregnant women, and those with chronic health conditions, are advised to receive vaccinations promptly [10]. Group 3: Vaccine Types and Administration - The available flu vaccines in China include inactivated (split) vaccines (trivalent/quadrivalent), inactivated (subunit) vaccines (trivalent/quadrivalent), and live attenuated vaccines (trivalent, nasal spray) [8]. - The difference between trivalent and quadrivalent vaccines lies in the number of virus strains they protect against, with quadrivalent covering an additional B strain, although the practical effectiveness may not differ significantly [8].