Nikhil Prasad Fact checked by:Thailand Medical News Team Nov 12, 2025 2 hours, 44 minutes ago
Medical News: A Nationwide Flu Epidemic Takes Hold
As November 2025 unfolds, Japan is grappling with an unusually aggressive influenza season that began five weeks ahead of schedule. Health authorities declared a nationwide epidemic in early October after cases spiked dramatically, overwhelming hospitals and prompting school closures across the country. This early onset marks the second-earliest flu peak in two decades, raising alarms about potential mutations in circulating strains and the need for heightened vigilance.
Japan's Early Flu Surge Worsens
Current Situation
Official data from the Ministry of Health, Labor and Welfare (MHLW) paints a stark picture. For the week of October 27 to November 2—encompassing week 44 of 2025—Japan recorded 57,424 influenza cases across approximately 3,000 designated medical institutions. This translates to an average of 14.90 patients per institution, more than double the previous week's figure of 6.29 and well above the alert threshold of 10, signaling a possible large-scale outbreak within four weeks.
By mid-November, infections had spread to all 47 prefectures, with hotspots in Miyagi (28.58 cases per institution), Kanagawa (28.47), and Saitama (27.91). Over 100 schools shuttered temporarily due to outbreaks, and more than 6,000 hospitalizations were reported by early November, disproportionately affecting children under 14.
This
Medical News underscores a broader trend: influenza A(H3N2) dominates, comprising over 60% of lab-confirmed cases per the National Institute of Infectious Diseases (NIID), followed by A(H1N1)pdm09 and B/Victoria-lineage viruses. A new H3N2 sublineage has also been detected that is causing disease severity among the vulnerable i.e. the old, young and immunocompromised.
NIID surveillance from sentinel sites shows positivity rates climbing to 25% in urban areas, with antiviral resistance low but monitored closely—no H275Y mutations detected in over 1,000 tested samples as of November 13.
Expert Insights and Impacts
Experts attribute the surge to waning post-COVID immunity, increased international travel, and possible viral adaptations enhancing transmissibility. "The current A strain is highly contagious across all ages," warns Reiko Saito, professor of public health at Niigata University. "Even mild symptoms warrant isolation and medical consultation, especially for the elderly and immunocompromised." Vaccination rates hover at 45% nationally, below the 70% target, exacerbating vulnerabilities.
Economically, the outbreak disrupts productivity, with absenteeism in schools and workplaces costing billions in yen. Pediatric wards report 40% bed occupancy from flu-related complications, straining resources amid ongoing avian influenza culls in poultry farms.
Outlook and Recommendations
Projections from NIID models suggest peak activity in late November to early December, potentially rivaling the record 317,812 weekly cases seen in December 2024.
However, robust surveillance and antiviral stockpiles offer hope for containment.
Authorities urge immediate vaccination, mask-wearing in crowds, and hand hygiene. For travelers, the WHO advises flu shots and symptom monitoring.
As Japan navigates this precocious pandemic, global health bodies watch closely—early patterns here could foreshadow Northern Hemisphere trends.
References:
https://www.mhlw.go.jp/content/001591812.pdf
https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/kenkou/kekkaku-kansenshou01/houdou_00023.html
For the latest on the flu crisis in Japan, keep on logging to Thailand
Medical News.
Read Also:
https://www.thailandmedical.news/news/breaking-new-mutant-h3n2-flu-virus-strain-with-7-genetic-changes-could-unleash-deadliest-global-flu-wave-in-decades
https://www.thailandmedical.news/articles/influenza-or-flu
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