Masks are reappearing on subway trains as influenza has arrived a month earlier than usual and COVID-19 cases have risen for a sixth straight week.
Influenza-like illness reached 13.3 cases per 1,000 outpatients in the 35th week of the current surveillance season, which ran from Aug. 23 to 29, the Korea Disease Control and Prevention Agency said on the 8th. The figure jumped in a single week from 9.2 the previous week and is more than double the 6.4 recorded in the same period a year earlier. The virus detection rate stood at 12.3%, more than 10 times the 1.3% seen in the same period of 2024 and the 1.1% in 2025.
Hospital data confirm the trend. Influenza patients admitted to hospital-level medical institutions rose to 162 in the 35th week from 43 in the 32nd week, while emergency room visits for influenza jumped more than fourfold to 1,606 from 373 over the same period. By age group, elementary school students aged 7 to 12 posted the highest rate at 36.5 per 1,000 outpatients as classes resumed, far above the 22.6 for children aged 1 to 6 and 14.6 for those aged 13 to 18.
The agency expects the rate for the current 36th week, from Aug. 30 to Sept. 5, to exceed the threshold for issuing an influenza epidemic advisory. The dominant strain circulating in the country is influenza A(H1N1)pdm09, which shows strong neutralizing responses to this season's vaccine strain, indicating that vaccination should be effective. No genetic mutations conferring drug resistance have been detected, leaving antiviral treatment available.
The picture abroad is similar. Japan reported 1.76 influenza cases per medical institution in the 35th week, already above its epidemic threshold of 1.0. That is five times the 0.35 recorded in the same period a year earlier and the earliest outbreak since sentinel surveillance began in 1999, excluding the 2009 swine flu pandemic. In southern China, the positivity rate climbed to 17.7% from the previous week, extending the spread.
COVID-19 is spreading at the same time. Hospital admissions for COVID-19 totaled 109 in the 35th week, fewer than the 406 recorded a year earlier but up for six consecutive weeks from 48 in the 32nd week. The detection rate for the coronavirus more than doubled to 11.7% from 5.7% four weeks earlier.
With the Chuseok holiday approaching, concerns about a "twindemic" of simultaneous influenza and COVID-19 increases are materializing.
The agency said it would proceed with vaccinations for high-risk groups without disruption. Influenza vaccinations begin on the 21st for children aged 6 months to 14 years and for pregnant women, and expand on the 28th to children who require a single dose.
Adults aged 65 and over can receive influenza and COVID-19 vaccines together starting Oct. 12. The agency urged people with fever or other symptoms to stay away from work and school, and advised older adults and others at high risk to seek medical care promptly.
