Objective To analyze the pathogen genomics and epidemiological characteristics of a respiratory adenovirus infection outbreak in schools in Tongzhou district of Beijing in 2023, and provide evidence for the prevention and control of the epidemic.

Methods The respiratory tract samples were collected from the respiatory infecton cases with fever of unknown origin in schools in Tongzhou for the detection of adenovirus nucleic acid by fluorescent polymerase chain reaction （PCR）. The hexon gene fragment of adenovirus was amplified by routine PCR for nucleotide sequence identification and preliminary typing. The whole genome sequence of adenovirus was obtained by whole genome targeted multiple amplification and sequencing for genetic phylogenetic tree analysis and monitoring of genomic variation.

Results A total of 4653 respiratory infection cases with fever of unknown origin were reported in 3 outbreaks of adenovirus infection in 14 schools in Tongzhou in 2023, and 89 cases were positive for adenovirus by fluorescent PCR. The hexon gene fragments of adenovirus were amplified by routine PCR in 63 positive samples, and 58 gene sequences were successfully amplified and sequenced. The Blast alignment and phylogenetic tree typing showed that human adenovirus B3 were detected in all the samples. The whole genome sequencing was conducted in 15 samples, the adenovirus genome coverage of the assembled sequences was more than 99%. Phylogenetic tree analysis showed that the adenovirus detected in the 15 samples were all closely related to the HAdV-B3 strain （MW748663.1） in Beijing in 2021 with the homology of >99.75%.

Conclusion The main genotype of adenovirus detected in the outbreaks in schools in Tongzhou in 2023 was HAdV-B3, and no obvious genomic variation was found.