OBJECTIVE To investigate the epidemiological characteristics of respiratory human adenovirus (HAdV) infections in hospitalized children in Ningbo, and to provide data for formulating infection prevention and control strategies for HAdV.

METHODS A total of 65 022 children hospitalized with respiratory infections at the Women and Children's Hospital of Ningbo University from Jul. 2019 to Dec. 2024 were selected as the study subjects. Multiple reverse transcription-polymerase chain reaction (RT-PCR) and capillary electrophoresis were used to detect 11 non-bacterial pathogens. Basic and clinical information of the children was collected for analysis.

RESULTS A total of 65 022 specimens were tested, with 4 292 cases tested positive for HAdV positivity, yielding a positive rate of 6.60%. The lowest positive rate was observed in 2023 (3.22%), while the highest was in 2024 (13.97%). Compared to the years 2019-2023, the overall HAdV positive rate was high in 2024, peaking at 26.80% in Jun., indicating an outbreak. The total HAdV positive rate was higher in boys (6.82%) than in girls (6.32%) (P=0.006). The highest HAdV positive rate was observed in the 2 to < 6 age group (9.00%), while the lowest was in the 0 to < 1 age group (2.33%). Among the HAdV-positive specimens, 2 658 cases (61.93%) were single infections, and 1 634 cases (38.07%) were co-infections. The non-bacterial respiratory pathogens with the highest co-infection rates were human rhinovirus (34.09%), Mycoplasma pneumoniae (20.44%) and human parainfluenza virus (5.75%).

CONCLUSIONS An outbreak of HAdV infections is observed among hospitalized children in Ningbo in 2024. Higher positive rates are found in boys aged 2 to < 6 years, with a certain proportion of co-infections.