Closed schools

Influenza, Japan declares epidemic: too many cases early and risk of spreading to Europe as well

Hundreds of schools closed, drastic measures also in Malaysia. The causes and the risk for other countries

by Massimo De Laurentiis

16 October 2025

2' min read

Translated by AI

Versione italiana

Key points

What causes and dangers for other countries
The causes of the epidemic
Further cases and consequences for Europe

2' min read

Translated by AI

Versione italiana

Over six thousand infected and more than a hundred schools closed. The flu season is starting five weeks earlier than expected and is also affecting Malaysia.

What are the causes and dangers for other countries

The Japanese health authorities declared a flu epidemic after the number of infections exceeded the alert threshold. As of 10 October, there were 6,013 confirmed cases.

This is unusual for the period, and indicates a wider and earlier spread of the virus than in previous years. Usually, flu outbreaks in Japan spread between the end of November and the beginning of December, but this year the virus started to circulate strongly as early as September, reaching levels considered epidemic within a few weeks.

The numbers

The virus has already caused the closure of more than a hundred schools, while among the 287 patients hospitalised in September, almost half were 14 years old or younger, a sign that children are among the most affected.

Experts report that the increase in the number of patients treated for influenza started five weeks earlier than usual, an advance never seen before.

The causes of the epidemic

The influenza A H3N2 strain, the same strain that has also caused a surge of cases in Australia and New Zealand in the last two months, coinciding with the end of winter in the southern hemisphere, is said to be responsible for the abnormal flu season in Japan.

Factors contributing to this advance include increased international travel, which facilitates the circulation of respiratory viruses, and the effects of climate change, which alters the seasonal patterns of spread of infections.

Experts also point to the low exposure to the virus in recent years, due to anti-Covid measures and the resulting drop in immunity, particularly among children and the elderly.

Further cases and consequences for Europe

The Japanese epidemic is not an isolated case. Malaysia had a similarly early influenza season, also dominated by the H3N2 strain. About six thousand students were infected and some schools were forced to suspend classes.

According to the Ministry of Health, there were 97 influenza outbreaks across the country last week, up from 14 the week before. Most were recorded in schools and kindergartens.

"We already have extensive experience in the management of infectious diseases thanks to the COVID-19 pandemic," the ministry's director-general Mohd Azam Ahmad said on Monday. "We have reminded schools to follow these guidelines, encouraging the use of face masks and the reduction of large group activities among students."

This year's flu wave shows an unprecedented breadth and speed of propagation, which threatens to affect the course of the flu season in the northern hemisphere as well. The H3N2 strain, in fact, could trigger epidemics in countries heading towards winter in Asia and Europe.