National Burden of Human Adenovirus Infections in China: A Community-Based Multiplier Modeling Study.

Human adenovirus (HAdV) is an important cause of respiratory infections, yet community-level burden estimates remain limited. We aimed to estimate post-pandemic HAdV burden in China. Using nationwide respiratory pathogen surveillance data and a multiplier model, we estimated the incidence of HAdV infections, symptomatic illnesses (SI), and medically attended illnesses (MAI) in China from 2023 to 2024. Age-, species-, and province-specific analyses were conducted. Uncertainty was assessed using Monte Carlo simulations. We estimated 44.21 million HAdV infections (95% UI, 26.68-77.08 million) over the 19-month study period, corresponding to an average monthly incidence of 1.58 per 1000 persons (95% UI, 1.01-2.61), equivalent to an annualized incidence of 18.96 per 1000 persons (95% UI, 12.12-31.32). The estimated average monthly incidences of SI and MAI were 0.41 (95% UI, 0.30-0.57) and 0.30 (95% UI, 0.21-0.40) per 1000 persons, corresponding to annualized incidences of 4.92 (95% UI, 3.60-6.84) and 3.60 (95% UI, 2.52-4.80) per 1000 persons, respectively. Children aged 0-4 years had the highest average monthly incidence (16.66 [95% UI, 10.26-28.54] per 1000 persons). HAdV species B showed higher incidence than species C among children aged 5-14 years. The highest incidence rates occurred in several south-central and southwestern provinces, including Hunan, Guangxi, Hubei, Guangdong, and Yunnan. HAdV imposed a substantial and under-recognized respiratory disease burden in China during the post-pandemic period. Children experienced the highest burden, and marked species-specific and geographic heterogeneity were observed. These findings provide community-based evidence to inform adenovirus surveillance and respiratory disease control strategies in China.