Norovirus surges in Seoul this summer ahead of chuseok holiday

Norovirus, a pathogen that normally peaks in winter, has been detected at unusually high levels in Seoul this summer. With temperatures approaching 30 degrees Celsius even during the chuseok holiday period, and with large family gatherings and increased travel typical of the season, health officials are urging the public to take extra care with food handling and hygiene.

The Seoul Metropolitan Government's Institute of Public Health and Environment reported Friday that norovirus detections in Seoul from June through August reached 141 cases this year — 70.5 times the two cases recorded during the same period last year. The cumulative count from January through August also hit 345 cases, already surpassing the full-year total of 242 cases recorded in 2025.

The institute conducted 3,575 viral food poisoning tests over the same period, exceeding the 3,038 tests carried out throughout all of last year.

Genetic analysis also revealed a notable shift. Unlike last year, the norovirus GII.3 genotype showed a marked increase this year. The institute said the unusual summer surge — a departure from the pathogen's typical winter-concentrated pattern — warrants continued surveillance.

Norovirus spreads easily not only through contaminated food and water but also through contact with infected individuals and exposure to vomit. Officials warned that the chuseok holiday, when family gatherings and shared meals are common, raises the risk of cluster infections.

To prevent infection, people should wash their hands with soap under running water for at least 30 seconds before and after cooking, before meals, and after using the restroom. Meat and seafood should be cooked thoroughly to the center, and shellfish such as oysters should be fully heated before consumption.

Water from groundwater or other unverified sources should be boiled before drinking. Anyone experiencing symptoms suggestive of norovirus infection — such as vomiting or diarrhea — should limit contact with others and avoid preparing food.

The institute said it plans to identify the causative pathogen through testing whenever a suspected food poisoning case arises, and to share results with relevant agencies including the Seoul Metropolitan Government, district offices and the Korea Disease Control and Prevention Agency to prevent further spread.

"We will do our utmost to closely monitor changing patterns of food poisoning outbreaks and, through swift and accurate testing and cause identification, create a safe food environment where citizens can feel at ease," institute director Park Ju-seong said.