Department of Statistics, Modeling and Economics, National Infection Service,Centre for Infectious Disease Surveillance and Control, Public Health England,London,UK.
Epidemiol Infect. 2019 Jan;147:e226. doi: 10.1017/S0950268819001109.
To control hepatitis A spread by vaccination, accurate estimation of transmissibility is vital. Regan et al. (2016) proposed a model of hepatitis A virus (HAV) transmission and used least squares to calibrate model to the 1991/1992 HAV outbreak in men who have sex with men (MSM) in Sydney, Australia. Based on the estimate of R0, they obtained the critical immunity of 70% and showed that when the proportion immune <70%, there is a definite chance for outbreaks to take place. The immunity level from previous surveys ranges from 32% to 64% after 1996 while no outbreaks in Australian MSMs have been reported since 1996. Further noticing the ill-distributed parameters, we argue that their estimate of R0 is not accurate. In this study, we revisited their model by Bayesian inference, which has privilege over least squares. We obtained the appropriate posterior distributions of parameters and the estimate of R0 ranges from 1.38 to 2.89, indicating a critical immunity of 65%. The reduction in critical immunity and outbreak probabilities predicts the absence of outbreaks in Australian MSMs since 1996. Our study shows the importance of using appropriate methods to provide reliable and accurate estimates of the model parameters especially the transmissibility.
为了控制疫苗接种引发的甲型肝炎传播，准确估计其传染性至关重要。Regan 等人（2016 年）提出了甲型肝炎病毒（HAV）传播模型，并采用最小二乘法对澳大利亚悉尼男男性行为者（MSM）中 1991/1992 年 HAV 暴发进行了模型校准。基于 R0 的估计值，他们得出了 70%的临界免疫力，并表明当免疫比例<70%时，暴发肯定会发生。自 1996 年以来，之前的调查显示免疫水平在 32%至 64%之间，但自 1996 年以来，澳大利亚 MSM 中未报告暴发。进一步注意到参数分布不均，我们认为他们的 R0 估计值不准确。在本研究中，我们通过贝叶斯推断重新研究了他们的模型，贝叶斯推断优于最小二乘法。我们获得了参数的适当后验分布，R0 的估计值范围为 1.38 至 2.89，表明临界免疫力为 65%。临界免疫力和暴发概率的降低预测了自 1996 年以来澳大利亚 MSM 中没有暴发的情况。我们的研究表明，特别是在传播力方面，使用适当的方法来提供可靠和准确的模型参数估计非常重要。
