For the first time in three years, Japan is now experiencing flu season nationwide.

Yomiuri Shimbun file photo
A dose of flu vaccine is drawn into a syringe.

Japan has entered the influenza season nationwide, the Health, Labor and Welfare Ministry said Wednesday.

The nationwide flu spread has begun for the first time in three years. In the past two years, there were no mass outbreaks, partly due to the effect of measures taken against the novel coronavirus pandemic.

According to preliminary figures compiled by the ministry, the number of flu patients newly reported by about 5,000 medical institutions designated as observation points nationwide reached 6,103 in the week to Dec. 25. The average number of patients per medical institution was 1.24, surpassing the level of 1.00 that is regarded as a yardstick to determine the start of the flu season.

According to estimates by the National Institute of Infectious Diseases, 7.29 million people became infected with influenza during the 2019-20 winter season, when the disease was last prevalent.

The ministry is concerned about dual outbreaks of COVID-19 and flu as the number of COVID-19 cases is increasing.