Longitudinal molecular epidemiology of human adenovirus in pediatric respiratory infections: a 12-year study in Korea (2008–2019)

Human adenovirus (HAdV) is a leading cause of respiratory infections, with clinical manifestations and disease severity varying by type. In this study, we analyzed HAdV types in South Korea over a 12-year period before the COVID-19 pandemic. From January 2008 to December 2019, HAdV isolates were prospectively collected from children with suspected respiratory infections at a single tertiary center. HAdV typing was performed through sequence analysis of hexon gene hypervariable regions (HVRs) 1–6. Among 350 HAdV isolates, members of four species (A, B, C, and E) and 10 types (1–6, 31, 34, 35, and 55) were identified. Overall, HAdV-3 was most prevalent (49.4%), followed by HAdV-2 (19.1%), HAdV-1 (14.6%), and HAdV-4 (6.6%). HAdV-3 caused four recurrent outbreaks at intervals of 3 to 4 years without significant genetic changes in the hexon HVRs. HAdV species C (types 1, 2, 5, and 6) was detected endemically throughout the study period. Notably, HAdV-55, which was associated with fatal cases in military recruits in South Korea during 2017–2018, appeared in pediatric cases. HAdV epidemiology studies are important for providing clinical data on circulating HAdVs in children, and there is a need for ongoing surveillance and research.