The Situation: An Early and Widespread Flu Season
The 2025 flu season in Japan began about five weeks earlier than usual, surprising both physicians and schools.
Experts believe that changing post-pandemic immunity patterns, increased travel, and shifts in climate may be contributing to this early wave.
We're seeing influenza behave differently after the COVID-19 years — earlier peaks and more severe clusters, especially among children, notes a public health official in Tokyo.
Why Children Are Especially Vulnerable
Influenza can affect anyone, but children — especially those under 12 — often experience the highest rates of infection and transmission.
1. Close contact in schools and daycare
Classrooms and childcare centers are ideal environments for viral spread. Shared spaces and close interactions make distancing difficult.
2. Lower baseline immunity
Young children may not have encountered certain influenza strains before, leaving their immune systems less prepared.
3. Greater risk of complications
While most children recover fully, influenza can sometimes trigger pneumonia, dehydration, bronchitis, or worsen chronic illnesses like asthma and diabetes.
4. Household spread
Children often bring the virus home, infecting parents, grandparents, and vulnerable family members.
Why Regular Flu Vaccination Matters
1. Proven protection
Influenza vaccines are updated each year to match the most likely circulating strains. Studies from Japan and globally show that vaccination reduces the risk of infection, hospitalization, and severe complications in children.
In fact, historical data from Japan's school vaccination program showed that childhood flu vaccination helped prevent thousands of deaths annually, even among older adults.
2. Timing is everything
With flu activity starting earlier, delaying vaccination can reduce protection. Experts recommend vaccinating before or at the onset of the season — typically in September or October in temperate regions.
3. Adapting to viral change
Influenza viruses mutate each year (a process called antigenic drift), which is why annual vaccination is essential — last year's shot may not protect against this year's strain.
4. Community and herd protection
When children are vaccinated, it doesn't just protect them — it helps reduce spread to others, protecting high-risk individuals and stabilizing healthcare systems.
What Parents and Schools Can Do
1. Vaccinate early
Book your child's flu shot as soon as it becomes available in your area.
2. Practice good hygiene
Encourage regular handwashing, mask use when unwell, and proper cough etiquette.
3. Keep sick children at home
Flu spreads rapidly in classrooms; staying home helps contain outbreaks.
4. Support school health programs
Schools can play a role by promoting vaccination drives, ensuring good ventilation, and communicating with parents about illness trends.
5. Stay informed
Monitor updates from local health authorities on flu activity and vaccine recommendations.
As influenza continues to evolve, regular vaccination remains one of the simplest and most effective ways to protect children's health, keep schools open, and prevent healthcare systems from becoming overwhelmed.