Japan Influenza Season 2024-2026

[Commonground]

Google Translation
Media [bolding is mine]
December 29, 2024

Why is influenza so prevalent? What to do if you have a fever during the New Year holidays

The number of influenza patients is rapidly increasing. Thirty-six prefectures nationwide have entered the "alert level" with more than 30 reported cases per designated medical institution. Some areas are experiencing historically high epidemics, so caution is needed regarding fevers during the New Year holidays.

Why is it so prevalent?

The number of influenza reports per designated medical institution is at a high level of 42.66. Some prefectures have reached the highest epidemic level since statistics began being collected, and the risk of infection is extremely high.

A designated medical institution is a medical institution that represents a region. The number of infected people per week is counted, and a warning level is 10 or more, and a warning level is 30 or more. In terms of personal experience, the warning level is "the number of infected people is increasing," and the warning level is "the number of infected people is quite high."

Looking at the number of reports by season in Osaka Prefecture, where the author lives, we can see that the first alert level epidemic since the COVID-19 pandemic has arrived (Figure 1). The number of cases has doubled since the previous week, so many areas may not have yet reached the peak of the epidemic.

continued: https://news.yahoo.co.jp/expert/arti...1d956a66a34ba8

[Commonground]

Flu Cases Reach Record High in Japan

2025.1.10
In the closing days of 2024, Japan recorded the highest number of weekly influenza cases since it started keeping records in 1999.


Japan set a new record of 317,812 weekly influenza cases for December 23–29, 2024, according to figures from the Ministry of Health, Labor, and Welfare, based on reports from 5,000 designated medical institutions across the country. This is the highest total since the current method of keeping records was introduced in April 1999. The average of 64.39 cases per institution is considerably more than the previous high of 57.09 in January 2019.

Kyūshū is particularly hard hit by the current outbreak, with 104.84 cases per medical institution in Ōita, 96.40 in Kagoshima, 94.36 in Saga, 92.56 in Kumamoto, and 90.24 in Miyazaki. All prefectures except Akita, Yamagata, Toyama, and Okinawa exceed the warning level of 30.

continued: https://www.nippon.com/en/japan-data...-in-japan.html

[Commonground]

[emphasis is mine]

8 Oct 2025

Japan’s flu season hits 5 weeks early amid fears of an evolving virus

The government has declared a nationwide flu epidemic, prompting calls for vaccinations and heightened vigilance


An unprecedented early surge in influenza cases has compelled Japan’s health authorities to declare a nationwide epidemic, as medical experts warn the virus may be evolving faster and spreading more easily than ever before.

The outbreak, which has caused hospital wards to fill up and schools across the country to close their doors, arrived five weeks ahead of schedule compared with last year.

Such an early and rapid spread suggests the influenza virus is adapting at an unprecedented pace. But this trend is not limited to Japan: researchers globally have observed similar patterns, prompting calls for heightened vigilance among residents and visitors alike.

“The flu season has started really early this year, but in the changing global environment this might become a more common scenario,” said Yoko Tsukamoto, a professor at the Health Sciences University of Hokkaido.

Emerging research indicates the virus is not only spreading more efficiently but may also be developing resistance to conventional treatments. Tsukamoto told This Week in Asia that these changes could help explain why Japan was experiencing its second-earliest flu outbreak in two decades.

“We are seeing this resistance in Japan, but it is also being reported in other parts of the world as well,” she said.

Health officials and scientists point to a confluence of factors behind the surge. Among them is the return of mass tourism in the post-pandemic era, which has accelerated the movement of people – and viruses – across borders.

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On October 3, Japan’s Ministry of Health declared an epidemic after 4,030 people were treated for influenza at designated medical institutions nationwide in the week beginning September 22, an increase of 957 cases from the previous week

continued: https://www.scmp.com/week-asia/healt...evolving-virus

[Shiloh]

Source: https://www.asiabusinessoutlook.com/...wid-10134.html


Japan Faces Severe Flu Outbreak, Schools Close, Hospitals Overrun
By: Asia Business Outlook Team | Monday, 13 October 2025
Japan Faces Severe Flu Outbreak, Schools Close, Hospitals Overrun

Japan is experiencing a severe influenza outbreak that is causing the government to take serious measures.

Health Ministry has proclaimed the country-wide epidemic of flu as the cases exceeded a critical level, averaging 1.04 number of patients per medical facility, which is not usually observed that early in the flu season.

There are over 4,000 hospitalized, and over 100 schools are closed, which makes the healthcare system of the country a major issue.

Health analysts are raising a red flag, that the influenza virus is altering at a rate higher than one could have anticipated.

The new development of these mutations may mean that vaccines and treatments may not keep up, becoming another challenge to doctors and researchers.

In response to the outbreak, the government is returning to familiar strategies of the COVID-19 days, such as asking people to wear masks, wash their hands and stay out of crowds...

[Pathfinder]

Translation Google

'It's never happened so early': Experts worry that Japan's flu outbreak will spread to other countries

An unusually early start to the flu epidemic, a large number of children hospitalized, schools closed... What if the flu virus currently raging in Japan spreads to other countries, particularly in Europe? This is what experts at the World Health Organization (WHO) fear.

by Véronique Molénat
Journalist
Published on October 21, 2025 at 3:07 AM
...
Since October 3rd, Japan has been experiencing a significant increase in flu cases . And that's not entirely normal!

Indeed, even though flu epidemics occur every year in winter, in this country they usually only occur towards the end of November. Thus, compared to other years, the increase in the number of people treated for the flu occurred five weeks earlier.

According to Ian Barr, researcher and deputy director of the Center for Reference and Research on Influenza of theWorld Health Organization(WHO), Japan experienced early onset of the season flu in recent years, but never this early. " We can see cases in October, but not in epidemic numbers ," the scientist says.

How can we explain the early arrival of this flu season?

There is currently no clear explanation for the early onset of the outbreak . However, the surge in international travel following the Covid-19 pandemic is one factor that may be responsible, according to Vinod Balasubramaniam, a molecular virologist at Monash University Malaysia.

THE climate change and the fact that few children and elderly people had previously been exposed to this virus are also among the factors involved in the early rise in infection cases.

Suspicions about the strain responsible for influenza A

Although the virus or viruses responsible have not yet been identified, suspicions fall on those of the strain responsible for influenza A, called H3N2. This strain has in fact circulated widely in Australia and New Zealand over the past two months (end of winter in the southern hemisphere) and also triggered an early influenza epidemic . However, at this time, it was not uncommon for many Australians to travel to Japan, which could have increased the transmissionof the virus between the two hemispheres.

The H3N2 virus hypothesis is reinforced by the fact that Malaysia is also experiencing an early flu season this year and that it was dominated by this family of viruses. According to a recent report from the Reuters news agency , more than 6,000 Malaysian students have been infected recently and many schools have also had to close theirdoors.

Towards contamination of European countries?

Vinod Balasubramaniam believes the flu epidemic in Japan is unlikely to become a global pandemic . Countries in the southern hemisphere are currently entering a warmer period, which should slow the virus's spread.

On the other hand, " it could very well leave Japan and spread to other neighboring countries or to countries located on travel routes from Japan " which are entering winter, estimates Ian Barr.

https://www.futura-sciences.com/sante/actualites/grippe-ca-ne-etait-jamais-produit-si-tot-experts-inquietent-epidemie-grippe-japon-etende-autres-pays-126610/

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See also:

14 October 2025

Japan declares a flu epidemic — what this means for other nations

Researchers say that the number of infections for this time of year is unusual.

By Rachel Fieldhouse

...

https://www.nature.com/articles/d41586-025-03367-z

[Commonground]

Nov 7, 2025
Flu cases in Japan exceed alert level, health ministry says

The average number of new influenza cases for each regularly monitored medical institution in Japan stood at 14.90 in the week through Sunday, exceeding the alert level of 10, the health ministry said Friday.

The figure, based on data reported by about 3,000 of such institutions nationwide, surged from 6.29 in the previous week, surpassing the alert level that indicates a possible large-scale outbreak within four weeks.

Of Japan's 47 prefectures, 25 saw their average top the alert level, with the highest figure seen in Miyagi at 28.58, followed by 28.47 in Kanagawa and 27.91 in Saitama, approaching the warning level of 30. Their counts were followed by 25.04 in Chiba, 24.99 in Hokkaido, 23.80 in Okinawa and 23.69 in Tokyo.

A total of 2,307 kindergartens, nursery schools, and elementary, junior high and senior high schools have experienced partial or complete closures due to the flu.

Japan entered this year's flu season at the end of September, its second-earliest in the past two decades.

https://www.japantimes.co.jp/news/2025/11/07/japan/science-health/flu-cases-alert/

[Commonground]

[Post #6, dated November 7th, there were 14.90 of new influenza cases for each regularly monitored medical institution in Japan]

TOKYO

The Japanese government said Friday the average number of influenza patients at designated medical institutions nationwide has hit warning levels at the fastest pace in 10 years, with some experts pointing to the rising number of inbound tourists as one of the likely factors for the epidemic's earlier-than-usual spread.

Across roughly 3,000 institutions, 145,526 patients were reported during the week from Nov. 10 to Sunday, averaging 37.73 people per facility and surpassing the warning level of 30, according to the Ministry of Health, Labor and Welfare.

The figure, 1.73 times higher than the previous week, means the warning level has been reached five weeks earlier than last season, with 24 of the country's 47 prefectures exceeding the threshold.

According to the health ministry, the most commonly reported virus was the type-A Hong Kong strain, which is the same strain that widely circulated during the winter of 2023.

Reiko Saito, a professor at Niigata University, said, "The strain was circulating between August and September in Hong Kong and Taiwan, and an increase in tourists traveling to Japan from those regions may have contributed to its rapid spread."

Other possible factors behind the rapid increase in infections, she said, include "the rapid drop in temperature, poor ventilation, and the extreme temperature fluctuations."

"Currently, the outbreak is mainly among children and students, but the number of adults infected is expected to increase toward the end of the year, when people will be on the move more frequently," she added.

The highest number of cases by prefecture was 80.02 in Miyagi Prefecture in northeastern Japan, followed by Saitama and Fukushima prefectures with 70.01 and 58.54, respectively.

While eastern Japan saw a rapid rise in general, the lowest numbers were recorded in Kochi, Tokushima, and Kagoshima prefectures.

A total of 5,777 elementary, junior high, and high schools have closed or partially closed due to the epidemic, an increase of about 2,000 from the previous week.

Influenza outbreaks typically occur in winter and the end of spring in Japan.

https://japantoday.com/category/national/japan's-flu-cases-reach-warning-level-at-fastest-pace-in-10-years

[Commonground]

6,300 Schools Closed, a 24-Fold Surge... Japan Struggles Amid Explosive Spread of 'K Variant'

Pubilshed 01 Dec.2025 14:23(KST)
Updated 01 Dec.2025 14:50(KST)

In Japan, the number of students contracting influenza (the flu) is surging, leading to a series of school classroom closures.
According to reports from Asahi Shimbun and Sankei Shimbun on December 1, the Ministry of Health, Labour and Welfare announced that, during the week of November 17 to 23, a total of 196,895 flu cases were reported by approximately 3,000 medical institutions nationwide, averaging 51.1 cases per institution. This figure is 1.35 times higher than the previous week, marking a 14th consecutive week of increases.
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There are also medical institutions where the number of flu patients treated from November 10 to 16 exceeded 100. T
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Professor Reiko Saito of Niigata University (Public Health) pointed out, "If children transmit the infection to their guardians or other family members, it can quickly spread throughout the community. Closing classes at the early stage of a flu outbreak is highly effective and is a necessary measure to prevent a major flu epidemic."

... https://cm.asiae.co.kr/en/article/2025120114104997452

[sharon sanders]

Original rpt here:

https://www.mhlw.go.jp/content/001600539.pdf

[Shiloh]

Source: https://www.nippon.com/en/news/yjj2025120100946/

New Flu Variant Subclade K Spreading in Japan
Society Dec 2, 2025 11:19 (JST)

Tokyo, Dec. 2 (Jiji Press)--A new flu virus variant called subclade K is spreading in Japan, a survey by the Japan Institute for Health Security has found.

The government-linked organization believes that the spread of the variant may be one of the reasons for this season’s flu outbreaks hitting Japan earlier than the average year. Subclade K had already been confirmed overseas.

In and after September, the JIHS examined influenza patients infected with the H3 strain, which is prevalent in the country this season, and detected subclade K in 22 out of the 23 samples. The risk of severe symptoms from subclade K is almost the same as that from existing flu viruses, according to the JIHS...