"Why Are So Many People Sick These Days?"... Flu Spreads Already, Three Weeks Earlier Than Last Year

Seoul Institute of Health and Environment: "Flu season started early"
Cases detected across all age groups...High-risk individuals urged to take precautions

This year, the influenza (flu) epidemic began three weeks earlier than last year, and the duration of the epidemic has tripled. Health authorities have urged people to get vaccinated and to follow personal hygiene guidelines.

The Seoul Institute of Health and Environment announced on October 4, 2026, "After testing patient and sewage samples, we found that this year’s flu epidemic started much earlier than usual."

The institute monitors the trends in respiratory infectious diseases in Seoul by testing samples from patients who exhibit respiratory symptoms throughout the year, and by analyzing viruses detected in sewage to track epidemic patterns.

This year, the increase in flu cases began earlier than in previous years, and the flu virus was detected in sewage samples earlier as well.

The number of flu patients began to rise at the end of August—three weeks earlier than last year, and 11 weeks earlier compared to 2019, before the COVID-19 outbreak. According to sewage monitoring, the virus was detected even earlier, starting at the end of July, which is six weeks ahead of last year.

The institute stated, "The flu epidemic period is getting longer, and cases are occurring across all age groups. High-risk groups such as children, pregnant women, and the elderly need to exercise caution."

The currently circulating flu virus is Influenza A (H1N1). The duration of the 2025–2026 flu epidemic is 16 weeks, more than three times longer than the 2024–2025 period, which lasted five weeks.

The Korea Disease Control and Prevention Agency (KDCA) issued an "Influenza Epidemic Advisory" on September 11, 2026, urging the public to be vaccinated and to comply with personal hygiene guidelines.

The national free flu vaccination program began on September 21, 2026. Eligible groups—including children aged six months to 14 years, pregnant women, and people aged 65 and older—can receive a single dose of the trivalent vaccine at designated medical institutions and public health centers.

Park Jusung, head of the Seoul Institute of Health and Environment, said, "We will closely monitor trends in respiratory infectious diseases, including influenza, and do our utmost for proactive epidemic prevention." He added, "Along with vaccination, I strongly encourage everyone to follow essential personal hygiene practices, such as handwashing and wearing masks."

This content was produced with the assistance of AI translation services.