South Korea health authorities have issued a nationwide influenza alert following an unseasonal summer surge in respiratory infections. According to the Korea Disease Control and Prevention Agency (KDCA), the flu advisory went into effect at midnight on September 11, 2026, prompting officials to urge public participation in the upcoming national vaccination program starting September 21.
Influenza transmission began climbing in late August, marking a departure from typical seasonal patterns. KDCA surveillance data shows that during the 36th week of the year, spanning from August 30 to September 5, the proportion of suspected outpatient flu cases reached 25.3 per 1,000 visits. This figure clears the epidemic threshold of 12.9 per 1,000 visits set for the 2026–2027 season. Last year’s outpatient rate during the comparable period sat at just 6.6 per 1,000 visits, meaning current outpatient suspicion rates are running at more than 3.8 times last year’s levels.
Hospitalization Rates and Vulnerable Populations
Hospital admissions have surged alongside outpatient visits. According to KDCA hospital-tier surveillance data, 300 patients were admitted for influenza during the 36th week of the year. That total represents a 1.8-fold increase over the previous week’s 166 admissions and a 13-fold spike compared to the 23 hospitalizations recorded during the same week last year.
While infections are rising across all age brackets, pediatric and adolescent populations are experiencing the most rapid spread. However, severe outcomes and hospitalizations concentrate heavily among older adults. Data from the health agency indicates that patients aged 65 and older account for 60% of all current flu-related hospitalizations. Respiratory virus detection rates at primary care clinics have climbed to 16.3%, up from 12.3% the previous week.
Virus Characteristics and Government Response
Laboratory analysis confirms that the A(H1N1)pdm09 strain is driving the current wave. KDCA officials stated that this circulating strain closely matches the World Health Organization’s recommended vaccine composition for the current season, and testing has revealed no mutations associated with antiviral resistance.
Ahead of the advisory, the KDCA convened a joint countermeasures meeting on August 8 with the Ministry of Education, the Ministry of Food and Drug Safety, the Ministry of Health and Welfare, and medical experts to review national response strategies. Under the newly enacted advisory, high-risk groups—including young children, pregnant women, adults aged 65 and older, and individuals with chronic medical conditions—can receive health insurance coverage for antiviral treatments without requiring a confirmatory diagnostic test, provided a physician deems it necessary.
National Vaccination Schedule and COVID-19 Trends
The national influenza immunization campaign will roll out sequentially beginning September 21. KDCA Commissioner Lim Seung-kan urged eligible groups to get vaccinated according to the designated schedule and recommended adhering to personal hygiene habits such as frequent handwashing, cough etiquette, and mask-wearing.
Simultaneously, health officials are tracking a concurrent rise in COVID-19 cases since August. Virus detection rates for COVID-19 reached 16.3%, up from 11.7% the prior week, alongside rising viral concentrations in municipal sewage samples. Hospital-tier surveillance recorded 193 COVID-19 admissions during the 36th week, which remains lower than the 433 admissions reported during the same period last year. Adults aged 65 and older account for 65.3% of current COVID-19 hospitalizations. While the BA.3.2 variant dominated infections from January to July, surveillance data shows the PQ.16.1.1 variant became the most prevalent strain in August.
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