Tokyo, Feb 4 (IANS): The number of flu patients across Japan in the week that ended on January 29 has reached epidemic warning levels in the country for the first time in three years, the health ministry said on Saturday.

According to data released by the National Institute of Infectious Diseases, the average number of patients per medical institution nationwide came to 10.36, surpassing the warning level benchmark of 10 per institution, reports Xinhua new agency.

The warning level suggests the possibility of an epidemic occurring in the coming four weeks.

About 5,000 regularly monitored medical institutions in all of Japan's 47 prefectures reported a total of more than 51,000 influenza cases during the seven-day period, the data showed.

By prefecture, the per-hospital number was the highest in Okinawa at 41.23, followed by Fukui at 25.38, Osaka at 24.34, and Fukuoka at 21.70.

Experts here warned that flu infections may further spread unlike normal years after strict Covid-19 countermeasures apparently helped keep flu infections at fairly low levels in 2021 and 2022.