日本流感疫情持续升级 变异株“亚型K”快速扩散

Core Viewpoint - Japan is experiencing a significant flu outbreak this winter, with the spread being the fastest in nearly a decade, leading to increased cases and public health measures [1][2]. Group 1: Flu Outbreak Statistics - The flu cases reported from November 17 to 23 reached 196,895 across approximately 3,000 medical institutions, averaging 51.12 cases per institution, which is 1.35 times higher than the previous week [1]. - 39 out of 47 prefectures in Japan have exceeded the government's alert level, with Miyagi (89.42 cases), Fukushima (86.71 cases), and Iwate (83.43 cases) being the most affected regions [1]. Group 2: Virus Mutation and Vaccine Efficacy - The rapid deterioration of the flu situation is linked to the spread of a new variant, subtype K of the H3N2 virus, which has been identified in over 90% of recent samples [1][2]. - The current flu vaccine for the 2025-26 season is designed based on different H3 virus lineages, but the effectiveness may decline faster due to lower neutralizing antibody matching [2]. Group 3: Public Health Recommendations - The Ministry of Health recommends vaccination for high-risk groups, including the elderly, children, pregnant women, and those with underlying health conditions, while emphasizing that vaccination alone cannot stop the outbreak [2]. - Public health measures suggested include frequent handwashing, wearing masks in enclosed spaces, ensuring indoor ventilation, and staying home when symptomatic [2]. Group 4: Concurrent COVID-19 Trends - There is a simultaneous decline in COVID-19 infections, with an average of 1.64 cases per medical institution, indicating a potential "see-saw" effect between flu and COVID-19 [3]. - Authorities warn that both flu and COVID-19 may continue to circulate together this winter, potentially straining medical resources and intensive care systems [3].