Flu season in Seoul starts three weeks earlier than last year
Flu seasons are not only arriving earlier; they are also lasting longer. The 2025-26 season lasted 16 weeks, more than three times as long as the five-week 2024-25 season.
A child receives a flu shot at a clinic in Seodaemun District, western Seoul, on Sept. 21, as Korea begins its national influenza vaccination program for children and pregnant women amid an earlier-than-usual flu season.
YONHAP
Flu season arrived in Seoul three weeks earlier than last year, and outbreaks are lasting longer, city health researchers said on Sunday.
“Tests of patient and wastewater samples show that this year’s flu season began earlier than in previous years, so preparation is needed,” the Seoul Metropolitan Research Institute of Public Health and Environment said.
The number of cases began rising in the 35th week of the year, or late August — 11 weeks earlier than in 2019, before the Covid-19 pandemic.
Wastewater surveillance, which measures virus concentrations in a city’s sewage and stormwater, detected the virus even earlier in late July.
Influenza, commonly known as the flu, comes in two main strains: A and B. The one now circulating is Influenza A, the subtype behind the 1918 Spanish flu and the 2009 swine flu pandemic. The virus is being increasingly detected in both patient and wastewater samples, according to the Seoul Metropolitan Government.
The Korea Disease Control and Prevention Agency (KDCA) issued an influenza advisory on Sept. 11 in response to the early outbreak. It also urged the public to get vaccinated and follow standard personal hygiene practices.
Flu seasons are also getting longer. The 2025-26 season lasted 16 weeks, more than three times as long as the five-week 2024-25 season, according to the research institute.
The government began its free national flu vaccination program on Sept. 21. Children aged 6 months to 14 years, pregnant women and adults 65 and older can get one free dose of the trivalent vaccine at contracted medical institutions and public health centers.
“Together with the KDCA, we will closely monitor trends in respiratory infectious diseases, including influenza, and do our best to prevent infections pre-emptively,” said Park Joo-seong, the head of the institute. “Along with getting vaccinated, I hope that people will practice basic personal hygiene etiquette, such as washing their hands and wearing masks.”
BY MOON HEE-CHUL [[email protected]]
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
