Early Seasonal Influenza Activity in Japan Overwhelms Hospitals and Closes Schools

Disease activity began five weeks earlier than is typical for flu season and is spreading rapidly among children. The rapid spread prompted the closure of schools and childcare centers to help reduce transmission.  

Japan has experienced premature starts to the flu season in recent years, although the start of the present season is unusual. The 2023/24 season, which started in the week of Oct 28-Nov 3, saw the most significant flu burden to date, with an estimated total of 18 million cases recorded, and the last week of 2024 reported the highest number of weekly cases since disease surveillance began in 1999.  

Health authorities predict the increased disease activity is due to international travel, changes in weather patterns, and a lack of exposure to the circulating virus due to the COVID-19 pandemic restrictions. A surge in influenza cases has also been observed across other Asian countries, including China, South Korea, Indonesia, Malaysia, and Thailand.  

Vulnerable populations, including children, the elderly, and those with chronic conditions, are disproportionately affected, due to the increased risk of complications and secondary impacts. While authorities have not implemented large-scale lockdowns or mandates, they are encouraging employers and schools to adopt flexible work arrangements, including telework and flexible attendance policies. Health officials in Japan have urged people, as well as tourists, to get vaccinated.  

In addition to vaccination, basic health precautions can help reduce the likelihood of exposure. These include:

• Frequent handwashing, and proper cough and sneeze etiquette
• Regular disinfection of surfaces  
• Social distancing and wearing a mask, especially in crowded public spaces such as transport and gatherings

This represents the most complete data available as of Oct. 20.    

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