Changes in respiratory virus infection trends during the COVID-19 pandemic in South Korea: the effectiveness of public health measures

Background/Aims Studies on the effectiveness of public health measures to prevent respiratory virus transmission in real-world settings are lacking. We investigated the effectiveness of universal mask use and adherence to other personal preventive measures on the changing viral respiratory infection patterns during the coronavirus disease 2019 (COVID-19) pandemic. Methods Data were extracted from the South Korean National Respiratory Virus Sentinel Surveillance System. During the COVID-19 pandemic, a cross-sectional survey on adherence to personal preventive measures was conducted. Additionally, the number of subway passengers was analyzed to estimate physical distancing compliance. Results During the pandemic, adherence to personal preventive measures significantly increased, particularly indoors and on public transportation. Respiratory virus trends were compared based on laboratory surveillance data of 47,675 patients with acute respiratory infections (2016 to 2020). The 2019 to 2020 influenza epidemic ended within 3 weeks, from the epidemic peak to the epidemic end, quickly ending the influenza season; with a 1.8- to 2.5-fold faster decline than in previous seasons. Previously, the overall respiratory virus positivity rate remained high after the influenza seasons had ended (47.7% to 69.9%). During the COVID-19 pandemic, this positive rate, 26.5%, was significantly lower than those in previous years. Hospital-based surveillance showed a decreased number of hospitalized patients with acute viral respiratory illnesses. Conclusions This study suggests that high compliance to the use of personal preventive measures in public might reduce the incidence of all respiratory virus infections and its hospitalization rates, with no additional quarantine, isolation, or contact screening