Background and Objectives: Nonpharmacologic interventions (NPIs), such as social distancing and preventive measures, were administered during the coronavirus disease (COVID-19) pandemic, which may influence the incidence of upper respiratory diseases (URDs). The present study compared the incidence of URDs during the COVID-19 pandemic and during the years prior to COVID-19, and investigated the effect of NPIs on URD in the nationwide general population.Subjects and Method This is an epidemiologic study based on the Korean National Health Insurance Database from March 2016 to February 2021. We compared the monthly incidence of URDs from March 2020 to February 2021 (12 months) with that of the past four years. A negative binomial regression model was used to evaluate the annual difference in the incidence of each URD and adjusting temperature, humidity, and the level of particulate matter 10 (PM10). Results: The monthly incidence of ‘the five common URDs’ in 2020 was significantly lower than that in the past four years. The incidence of other chronic diseases, however, such as hypertension and diabetes mellitus, was comparable or higher in the past four years. Among the five common URDs, influenza virus infections decreased most dramatically, nearing 99%, from 296.4-377.1 per 100000 people during the period of 2016 to 2019 to 3.7 per 100000 people in 2020. Conclusion The present study shows that the incidence of ‘five common URDs’ significantly decreased during the era of COVID-19 in Korea. We believe that nationwide NPI might prevent the transmission of COVID-19 as well as other infectious sources associated with URDs.