[Changes in Patterns of Respiratory Virus since the Coronavirus Disease 2019 Pandemic (Until April 2023)]

The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted the trend of influenza and respiratory virus infections, leading to substantial changes in their seasonal patterns. This study aimed to describe the impact of COVID-19 on the pattern of respiratory virus infections by analyzing the trend (such as detection rate) of respiratory pathogens in patients with respiratory symptoms who visited sentinel sites and by examining the surveillance results of inpatient surveillance at general hospitals. The analysis covers a 3-year period before the COVID-19 outbreak (2017-2019) and the period following the ease of social distancing measures during the COVID-19 pandemic (2022-2023). As of 2023, respiratory viruses such as influenza virus, rhinovirus, human coronavirus, adenovirus, and human bocavirus continue to show seasonal patterns similar to those observed before the COVID-19 pandemic. However, respiratory syncytial virus, parainfluenza virus, and human metapneumovirus, have shown different seasonal patterns. During the spring of 2023, with the exception of human coronavirus, the detection rate and hospitalization of other respiratory viruses have shown an increasing trend. This emphasizes the need for continuous monitoring and information sharing regarding the overall increase and changes in respiratory viruses at the end of COVID-19 pandemic period.