Rotavirus-associated disease burden and clinical severity in vaccine-naive Chinese infants: A synthesised Bayesian framework

Background: Despite rotavirus (RV) being the leading viral cause of childhood diarrhoea in China, burden estimates and severity profile associated with natural infection remain limited.We aimed to quantify RV burden and clinical progression among unvaccinated Chinese infants using vaccine clinical trial data. Methods:We pooled efficacy and immunogenicity data from placebo arms of RV clinical trials conducted in China.A six-state burden pyramid (susceptible, infected, symptomatic, severe, hospitalised and dead) described the natural history.We used a unified Bayesian framework to estimate transition probabilities between adjacent states and derived RVassociated burden and clinical severity metrics.Sensitivity analyses restricted the dataset to trials with > 3000 observations and to infants enrolled at 6-16 weeks. Results:We included 20,248 observations from 11,235 eligible infants.We estimated an annual RV infection rate of 495.8 (95% credible interval [CrI]: 314.1-782.8)per 1,000 infants.Only 10.3% (4.8-21.8),4.1% (2.0-8.5),1.5% (0.8-2.9) and 0.09% (0.02-0.5) of infections progressed to symptomatic, severe, hospitalised and fatal cases over one year. Conclusion:Natural RV infection is frequent but predominantly subclinical, indicating that surveillance based on severe or hospitalised cases underestimates the true burden.Our findings support RV vaccine introduction in China's national immunisation program.