Background: Acute respiratory infection (ARI) is the most common infectious disease in all ages and genders worldwide. Respiratory microorganisms such as respiratory viruses, are commonly responsible for causing ARI. COVID-19 is still prevalent in Korea. The implementation of lockdown and strict control measures, the mandatory wearing of masks, and social distancing are critical steps for controlling the risk of COVID-19 spread. This study was conducted to find out how these changes in daily lives impacted the distribution of respiratory microorganisms.
Methods: A retrospective study was conducted to identify the incidence and distribution patterns of ARI-causing respiratory microorganisms before (Period Ⅰ) and during the COVID-19 pandemic (Period Ⅱ) in terms of detection method, age, month, and season. In particular, data in Periods Ⅰ and Ⅱ were compared for eight major kinds of respiratory microorganisms: adenovirus (AdV), human metapneumovirus (HMPV), human rhinovirus/enterovirus (Rhino/Entero), influenza virus (Flu) A, Flu B, human parainfluenza virus (HPIV) 3, respiratory syncytial virus, and Mycoplasma pneumoniae.
Results: A total of 27,191 respiratory specimens were tested, of which 5,513 were obtained from children and adolescents (age groups 1 ⁓ 5) and 21,678 from adults (age group 6). The overall positive rates for at least one respiratory microorganism in Periods Ⅰ and Ⅱ were 23.1% (1,199/5,193) and 4.9% (1,070/21,998), respectively (p < 0.001). The overall positive rates in male and female patients were significantly different (8.7% vs. 7.9%; p = 0.016). On the FilmArray™ RP assay, positive rates in all age groups decreased significantly in Period Ⅱ compared with Period Ⅰ. AdV, Rhino/Entero, and Flu A were detected in all four seasons, but HMPV and HPIV3 were not detected. The overall positive rates on FilmArray and the Flu antigen test in Period Ⅱ were significantly decreased. In the COVID-19 test, the positive rates were high in March and April 2020, and decreased thereafter, but these increased again in the winter of 2020/2021.
Conclusions: Life changes due to COVID-19 pandemic have had a significant impact on the distribution of respiratory microorganisms; our study results might provide useful information on respiratory virus epidemiology.