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.
“We are seeing a greater circulation of people, both in Japan and globally, with people taking the virus to new places, which is another factor behind the virus adapting to new environments,” Tsukamoto said.
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.
The ministry said the caseload had crossed the epidemic threshold, with an average of 1.04 patients per institution.
During the same period, 135 schools, kindergartens and childcare centres were closed due to outbreaks among children, a figure three times higher than the same week last year.
In Yamagata prefecture, northern Japan, a primary school was abruptly closed on Monday after 22 of its 36 pupils developed flu symptoms.
Okinawa prefecture has been especially hard hit, as have Tokyo and Kagoshima. Overall, 28 of Japan’s 47 prefectures have reported an increase in cases.
With the peak of the flu season expected to hit earlier than usual, Tsukamoto urged the public to seek vaccination promptly.
“For people who are healthy, the flu should not be too dangerous, although it could be unpleasant,” she said, adding that young children, the elderly and anyone with underlying health conditions were recommended to get vaccinated.
“People need to take common sense precautions,” Tsukamoto added. “I’m going to get my vaccination later this week and people should wash their hands regularly, even if they do not think they have come in contact with the virus.”
The warning extends to foreign visitors as well, as Japan continues to welcome tourists in large numbers. Ashley Harvey, a travel marketing analyst with more than 15 years’ experience in Japan, echoed Tsukamoto’s calls for caution.
“I am not sure if the strain we are seeing in Japan is the same as in other countries, so I do not know if a vaccination before travelling to Japan will be effective,” he said. “But there are other precautions that can be.”
Harvey likewise cited handwashing, the importance of well-ventilated spaces and the personal decision to wear a face mask.
