Flu season appears to be in full swing, with an estimated 1.64 million people across Japan coming down with the symptoms in the week through Feb. 7, the health ministry said.
Almost 6,000 day care centers and elementary and junior high schools shut down or were operating under reduced hours.
The flu season began in earnest later than in the last several years, but the number of cases is close to average, the ministry said Monday.
Flu patient data are based on reports from roughly 5,000 hospitals and other medical institutions across the country.
Of the 47 prefectures, Kanagawa had the most flu patients per medical institution from Feb. 1 to Feb. 7 at 48.95, followed by Saitama at 47.52, Aichi at 45.24, Chiba at 44.91 and Fukuoka at 44.40. The rate in Tokyo was 39.43.
The number of reported flu cases was up from the pervious week in every prefecture.
About 400,000 children aged 5 to 9 were diagnosed with the flu, making up the largest age group, followed by about 220,000 children between birth and 4 years old, and roughly 220,000 children aged 10 to 14.
The most prevalent type of flu over the last five weeks was the type-A H1N1 strain that became virulent in 2009 as a new type of flu, followed by type-B flu.