日本疫情爆发！数千学校紧急关闭，一周报告超11万例，每家诊所平均30人

Core Insights - The Japanese Ministry of Health, Labour and Welfare reported that from January 26 to February 1, the average number of flu cases per designated medical institution reached 30.03, indicating a return to the flu epidemic alert level [1] - A total of 114,291 flu cases were reported across over 3,800 designated medical institutions in Japan during the same week, surpassing the epidemic alert threshold of 30 cases per institution [1] - The resurgence of flu cases has led to 6,415 educational facilities in Japan suspending or partially suspending classes, with nearly 60% of these being elementary schools [1] Virus Strains - The majority of flu cases reported in December were attributed to the H3N2 virus's "sub-branch K" variant, which is believed to be a significant factor in the rapid spread of the flu [1] - Data indicates that starting from the end of 2025, the proportion of flu cases caused by the B-type influenza virus is expected to increase [1] - Experts suggest that the alternating prevalence of these two virus strains may contribute to the fluctuations in flu activity, leading to a resurgence after a period of decline [1]