Abstract
Social distancing has been adopted as one of basic protective measures against coronavirus disease 2019 (COVID-19). During 2019-2020 season, influenza epidemic period was exceptionally short and epidemic peak was low in comparison with previous seasons in Korea. Influenza epidemic pattern was bimodal in 2016-2017 and 2018-2019 seasons, however, influenza viruses have rarely been circulating in spring, 2020 in Korea. Although multiple factors could affect the size of influenza epidemic, extensive application of nonpharmaceutical interventions including mask wearing and social distancing in response to COVID-19 seems to be a major factor of reduced influenza epidemic. Social distancing measures with high feasibility and high acceptability should be implemented even if severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are developed in the future. Establishment of guideline for workplace social distancing is needed and it would contribute to reduce disease burden of influenza, especially in vaccine mismatch year.