Most South Koreans know that washing their hands helps prevent infectious diseases, yet only about one in 10 actually does it properly — scrubbing with soap for at least 30 seconds. Over the same period, influenza cases rose for a fourth consecutive week, prompting the Korea Disease Control and Prevention Agency to issue a flu epidemic alert.
According to a 2025 survey on infection-prevention behavior conducted by the Korea Disease Control and Prevention Agency and the National Medical Center, 84.1% of respondents said they wash their hands after using the toilet and 45% said they use soap, both up from a year earlier. But the share practicing "proper handwashing" — rubbing all surfaces of the hands with soap under running water for at least 30 seconds — was 10.3%, virtually unchanged from 10.5% the previous year. The figure stood at 11.2% in the 2023 survey. Handwashing itself has become more common, but the method and duration still fall short of the standard.
The agency says washing hands properly for at least 30 seconds can prevent 50% to 70% of most infectious diseases, including waterborne illnesses and influenza. On its official social media accounts, the agency has said that washing with soap for 30 seconds or longer can cut diarrheal illness by 30% and respiratory illness by 20%.
The U.S. Centers for Disease Control and Prevention cites similar figures. The CDC says community handwashing education reduces diarrheal illness by 23% to 40%, school absences from gastrointestinal illness by 29% to 57%, diarrheal illness among people with weakened immune systems by about 58%, and respiratory illness in the general population by 16% to 21%. The two countries differ on duration, however. Korea's agency sets a benchmark of at least 30 seconds, while the CDC recommends scrubbing for a minimum of 20 seconds.
The spread of respiratory infections during the seasonal transition is showing up in the data. Under the agency's sentinel surveillance for infectious diseases, the rate of suspected influenza cases in the 36th week of 2026, covering Aug. 30 to Sept. 5, reached 25.3 per 1,000 outpatients — roughly double the epidemic threshold of 12.9 for this season. The rate climbed for four straight weeks, from 7.5 in week 33 to 9.2 in week 34, 13.3 in week 35 and 25.3 in week 36, about 3.8 times the 6.6 recorded a year earlier. By age group, the rate was 75.1 among children aged 7 to 12, 49.8 among those aged 1 to 6 and 31.3 among those aged 13 to 18, with the sharpest increases among school-age children and infants. Hospital admissions also rose, to 300 in week 36 from 166 the previous week. The agency issued an influenza epidemic alert in response.
