Japan’s flu season began in September, earlier than usual amid tourism surge

Influenza outbreaks started in Japan in late September, earlier than usual, partly because of increases in cross-border travel.

According to the health ministry, the number of flu patients reported by regularly monitored medical institutions across the country in the week to Oct. 26 stood at 6.29 per facility. By prefecture, Okinawa topped the list, with 19.40, followed by three prefectures neighboring Tokyo — Kanagawa, with 11.88, Chiba, with 11.82, and Saitama, with 11.73.

The number began to exceed 1.0 in late September — the second earliest increase in 20 years excluding the 2023-24 season, when outbreaks continued yearlong. A reading of 1.0 or higher suggests the start of a flu season.