Epidemiology of Respiratory Tract Infections Using Multiplex PCR in a Japanese Acute Care Hospital During the COVID19 Pandemic

Introduction: We aimed to investigate the epidemiology of respiratory infections by season and age during the COVID-19 pandemic in a Japanese acute care hospital using multiplex PCR testing. Methods: We detected 21 pathogens in specimens from outpatients with respiratory symptoms at the Nara Prefecture General Medical Center using the multiplex PCR-based FilmArray Respiratory Panel 2.1 (bioMérieux). Results: Of the 3,177 cases, 1,215 (38.2 %) were infected with at least one causative virus, and 1,641 viruses were detected. The most common viruses detected were human rhinovirus/enterovirus (n=655) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (n=264). Additionaly, 321 (10.1%) of these cases were infected with two or more overlapping viruses. There were 23 cases of co-infection with SARS-CoV-2 and other viruses. In the winter months from December 2020 to March 2021, the number of detected viruses was relatively low, followed by the surge of human rhinovirus/enterovirus, respiratory syncytial virus (RSV), and parainfluenza type 3 in the spring and summer of 2021. While the number of human rhinovirus/entero-virus remained relatively high after the 2021 summer, the number of other viruses detected since September 2021 was low. After December 2021, the number of SARS-CoV-2 increased rapidly. Conclusions: Continuous monitoring of the epidemiology of respiratory infection is important to understand the prolonged impact of the COVID-19 pandemic. Funding Information: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Declaration of Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Ethics Approval Statement: The institutional review board of the Nara Prefecture General Medical Center approved the use of the opt-out consent method for this study (No. 671);therefore, the requirement for written informed consent was waived. In addition, the study was found to be in compliance with all regulations.