TOKYO, Oct. 15 (Xinhua) -- The number of influenza cases in Japan during the week of Sept. 29 to Oct. 5 was 1.5 times higher than the previous week, data from the Japan Institute for Health Security (JIHS) showed.
A total of 6,013 cases were reported across Japan during the week ending on Oct. 5, averaging 1.56 cases per sentinel medical institution, compared with 1.04 cases the previous week, the data showed.
Okinawa Prefecture reported the highest number, with an average of 12.18 cases per institution, followed by Tokyo (3.3) and Miyazaki (2.89).
This year's flu season has started about a month earlier than usual in Japan, driven by a combination of factors including an increase in overseas travel, declining public vigilance, and climate fluctuations.
Under Japan's monitoring standards, when the average weekly number of influenza cases per designated medical institution exceeds one, it marks the beginning of the flu season. If the number rises above 10, it reaches the "alert level."
Based on this criterion, Japan's Ministry of Health, Labor and Welfare declared the start of the nationwide flu season on Oct. 3, after the weekly average reached 1.04 during the week of Sept. 22-28.
This was five weeks earlier than in 2024 and the second-earliest start since the current statistical method was introduced in 1999.
The data also showed that the number of new weekly influenza cases has increased for seven consecutive weeks since mid-August. As the flu spreads, 620 kindergartens, nursery schools, and elementary and secondary schools across Japan have been fully or partially closed as of Oct. 5. ■