The Korea Disease Control and Prevention Agency issued an influenza advisory at the start of the 2026-2027 season, responding to an outbreak that arrived earlier than in previous years. The spread has been most pronounced among children aged 7 to 12, or elementary school age.
The agency said the advisory took effect at midnight on the 11th. After influenza cases climbed above levels seen in previous years, the agency reviewed the outbreak and response measures with the Ministry of Health and Welfare, the Ministry of Food and Drug Safety, the Ministry of Education and medical experts. The advisory was issued because the share of patients with influenza-like illness exceeded the epidemic threshold and the virus detection rate topped 5%.
Sentinel surveillance at clinics found 25.3 influenza-like illness cases per 1,000 outpatients in the 36th week of the year, covering Aug. 30 to Sept. 5. That is about twice this season's epidemic threshold of 12.9 and roughly 3.8 times the 6.6 recorded in the same period a year earlier. The rate rose rapidly over the past four weeks, from 7.5 to 9.2, then 13.3 and 25.3.
By age group, those aged 7 to 12 posted the highest rate at 75.1 per 1,000, followed by children aged 1 to 6 at 49.8 and teenagers aged 13 to 18 at 31.3, showing elevated incidence among school-age children and young children. The rate was 23.5 for those aged 19 to 49, 11.8 for those aged 50 to 64 and 8.8 for those aged 65 and over.
Hospitalizations also jumped sharply. Sentinel hospitals reported 300 influenza inpatients in the 36th week, up about 81% from 166 the previous week and roughly 13 times the 23 recorded in the same period last year. Patients aged 65 and over accounted for 180 of the total, or 60%.
The dominant strain in circulation is influenza A(H1N1)pdm09, which the agency confirmed is similar to the strain used in this season's vaccine. The virus detection rate rose over the past four weeks from 5.4% to 10.0%, then 12.3% and 16.3%. No mutations affecting resistance to antiviral drugs were detected.
While the advisory is in effect, high-risk patients — including children, pregnant women, people aged 65 and over, immunocompromised patients and those with underlying conditions — can receive antiviral treatment covered by national health insurance without a separate diagnostic test if a physician prescribes it.
The agency plans to begin its state influenza vaccination program in phases from the 21st. Because the outbreak began earlier than usual, it is also considering adjusting the schedule to prioritize high-risk groups such as immunocompromised patients. Nursing hospitals and long-term care facilities will be allowed to begin vaccinations as soon as supplies arrive, depending on transmission levels in their communities.
"This season's influenza outbreak is starting quickly, so high-risk groups vulnerable to influenza need to take particular care," KDCA Commissioner Lim Seung-kwan said. "Older people aged 65 and over and immunocompromised patients should visit a medical institution early if they develop a fever or respiratory symptoms, so they can receive appropriate diagnosis and treatment."
