Japan Influenza Season 2025-26

[Commonground]

Tokyo issues first influenza warning for November since 2009
9 hours ago

The Tokyo Metropolitan Government has issued an influenza warning as patient numbers in Tokyo exceeded a designated reference level.

The alert, issued on Thursday, is the first for November since 2009.

The number of flu cases reported in Tokyo for the week through November 9 rose to 29.03 people per medical institution, an increase of 5.34 from the previous week.

Out of 31 public health centers in Tokyo, those reporting flu patients exceeding 30 per medical institution in their jurisdictions rose to 12. The number of people living in those 12 jurisdictions exceeded 30 percent of Tokyo's total population designated by the metropolitan government for triggering the warning.

Between September this year and Sunday, the number of preschools, elementary schools, junior high schools and high schools taking steps, such as fully or partially closing, numbered 1,125. That is more than 11-times the total of 99 recorded during the same period last year.

The metropolitan government is urging people to take measures to prevent infection such as frequently washing hands, wearing masks when appropriate and avoiding crowded places.

https://www3.nhk.or.jp/nhkworld/en/news/20251113_24/

[Commonground]

December 3, 2025
Japan’s flu season comes early as new variant spreads



A new influenza variant spreading across Japan may be behind the increase in early outbreaks this year, the Japan Institute for Health Security (JIHS) has said.

The new strain, called “Subclade K” is a variant of the type A flu virus, which typically spreads around the beginning of the flu season, while type B tends to spread later on.



Of the influenza patients JIHS examined since September, they found that 22 out of 23 samples — around 96% — were infected with the new strain.

The risk of developing severe symptoms from Subclade K is no higher than other strains, according to JIHS. The institute also added that the new strain is not necessarily more contagious.

As the flu becomes more widespread, infecting more people, it would mean more people would experience severe symptoms, resulting in more patients being hospitalized. Considering when cases have peaked in previous years, it is very likely that the high levels of infections seen now will continue in the nation, making it necessary for preventative measures to be taken, the JIHS said.

According to the most recent numbers by the health ministry, around196,895 flu cases were reported by around3,800 medical institutions during the week through Nov. 23.

On average, there were 51.12 patients per medical facility — well above the threshold of 30 patients for issuing a warning. During the same period last year, there were only 2.36 patients per medical facility, suggesting the early onset of the flu season this year.

At its peak during the end of December, the flu season from the year prior saw more than 64.39 patients per facility.

Warnings have been issued in 39 prefectures, with the highest rate of patients seen in the Tohoku region.

... https://www.japantimes.co.jp/news/20...flu-season/