The latest data released by Japan’s National Institute of Health Crisis Management on the 2nd shows that from November 17 to 23, a total of 196,895 influenza cases were reported by over 3,800 designated medical institutions across Japan, with an average of 51.12 cases reported per institution.
According to the data, in the 47th week of 2025 (November 17 to 23), the average number of influenza cases reported per designated medical institution in Japan was 51.12, approximately 1.35 times higher than the previous week. Last year, the weekly average cases per institution in Japan surpassed 50 in the 52nd week, which has happened more than a month earlier this year.
The Japanese Ministry of Health, Labour and Welfare stated that among the influenza viruses currently circulating in Japan, more than 90% are the A(H3N2) “sub-lineage K” variant, which may be one of the main reasons for the rapid spread of influenza this season.
The ministry pointed out that, of the 23 influenza virus samples collected and identified as A(H3) subtype from September to November 5 in Japan, 22 were the “sub-lineage K” variant, accounting for about 96%. This variant spreads more rapidly.