Human adenovirus in Taiwan, 2019-2023.

Human adenovirus (HAdV) is a common cause of acute respiratory infections, affecting both the upper and lower respiratory tract. In this study, we retrospectively analyzed the epidemiology of HAdV by using data from the National Community Viral Surveillance System in Taiwan from 2019 to 2023. The average detection rate during this period was 3.4%, with the highest detection rate observed in 2023, at 6.6%, which is more than 3-4 times the detection rate observed from 2020 to 2022. In this study, a total of 1,565 HAdV isolates were sequenced from 2019 to 2023, and six species and 17 HAdV types were identified. Among these, HAdV-B3 and HAdV-C2 were the most prevalent types. HAdV infections occurred year-round in Taiwan, with statistical analysis revealing that 91.9% of cases affected children under nine years of age, with no significant difference between males and females. Although HAdV infections are typically mild and self-limiting, some patients presented with severe complications, such as pneumonia and central nervous system (CNS) symptoms. Additionally, several patients with HAdV infection were coinfected with other respiratory pathogens. Our findings indicate that the prevalent HAdV types in Taiwan are genetically diverse and coexist in the community, emphasizing the need for continued epidemiological surveillance. Given the significant role of HAdV in acute respiratory disease, further investigation into its molecular epidemiology and clinical characteristics is essential for the development of effective prevention and control strategies.