重组禽流感病毒（H5+H7）二价灭活疫苗对降低人感染A(H7N9)禽流感病毒传播的有效性研究

2013-2017年，我国经历了5波人感染A(H7N9)禽流感病毒暴发疫情。2017年9月，我国开始实施对家禽强制免疫重组禽流感病毒（H5+H7）二价灭活疫苗。此后，观察到的人感染A(H7N9)病例数显著减少，每年均低于3例。目前尚无研究定量评估家禽A(H7N9)疫苗免疫接种项目对降低人感染A(H7N9)病毒风险的有效性。本研究将基于泊松概率函数与随机效应模型，估算人群中的A(H7N9)期望感染数；构建传播动力学模型，基于贝叶斯理论框架下的马尔科夫链蒙特卡洛方法，估算家禽A(H7N9)疫苗强制免疫措施对人感染A(H7N9)的关键传播动力学参数（如：感染力、R0与Re等）、各时点人感染A(H7N9)概率分布的影响，并确定该措施的净效应。研究结果将为制定基于证据的人感染A(H7N9)禽流感防控策略、评估A(H7N9)禽流感病毒引起大流行的潜在风险提供科学依据。

China experienced 5 epidemic waves of human infections with A (H7N9) avian influenza virus from 2013 to 2017. Recombinant avian influenza virus (H5+H7) bivalent inactivated vaccine (i.e., H5/H7 bivalent inactivated vaccine) has been introduced in domestic poultry since September 2017. From then on, the number of observed human cases infected with A(H7N9) virus met a significant decrease, with lower than 3 cases each year. However, there is a lack of quantitative study on estimating the effectiveness of such program. Poisson likelihood function and random effects model are designed to estimate the expected number of A(H7N9) infections. On the basis of Markov chain Monte Carlo (MCMC) method combined with Bayesian theory, transmission models will be constructed to estimate the influence of compulsory poultry vaccination on key parameters of A(H7N9) transmissions (e.g., force of infection, R0 and Re) and probability distribution of human infection with A (H7N9) avian influenza virus at each time point, and also to clarify net effect of H5/H7 bivalent inactivated vaccine in poultry on A(H7N9) epidemics in human. Our research results can supply essential scientific data to evidenced-based technical recommendations for preventing and controlling A(H7N9) epidemics in human, and to the assessment of potential risks of pandemic caused by A(H7N9)virus.