Influenza outbreak spreads early in Japan, including Niigata

Influenza is spreading at an unusually early rate across Japan, with Niigata Prefecture officially entering an epidemic period. As of late August 2026, the number of patients reported per medical institution in Niigata more than doubled compared to the previous week, significantly exceeding the epidemic threshold of one patient per institution.

Medical experts, including Dr. Masaaki Okajima of Mirai Clinic Minami-Sasaguchi, suggest the surge is driven by a different strain of the virus than last year, leaving many without existing immunity. The increase in infections is particularly noted among younger generations following the Obon holiday period and increased international travel.

Health officials warn that the current warm weather makes it difficult to distinguish influenza symptoms from heatstroke, as approximately 20 percent of patients may not present with a fever. Furthermore, influenza vaccines are not expected to be widely available until October. Experts recommend maintaining basic hygiene, such as handwashing, gargling, and ventilation, and wearing masks in crowded areas to prevent further spread.