Reactive and pre-emptive vaccination strategies to control hepatitis E infection in emergency and refugee settings: A modelling study
Reactive and pre-emptive vaccination strategies to control hepatitis E infection in emergency and refugee settings: A modelling study
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DOI：
10.1101/219154
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发表时间：
2017-05
影响因子：
3.8
通讯作者：
B. Cooper;L. White;M. R. Siddiqui
中科院分区：
文献类型：
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作者：
B. Cooper;L. White;M. R. Siddiqui
戊型肝炎病毒（HEV）是紧急情况和难民营环境中发病和死亡的重要原因。有症状感染与孕妇病死率约20%有关。然而，人们对其流行病学了解甚少，在疫情暴发环境中免疫接种的潜在影响也不确定。我们的目的是估计戊肝病毒的关键流行病学参数，并评估反应性疫苗接种（为应对流行病而启动）和先发制人疫苗接种的潜在影响。方法：我们分析了2007-2009年发生在乌干达难民营的世界上最大的戊型肝炎疫情之一的数据，使用传播动态模型来估计流行病学参数，并评估反应性和预防性疫苗接种策略的潜在影响。在基线假设下，我们估计HEV的基本繁殖数在3.9 （95% CrI 2.8, 5.4）到8.9（5.4,14.2）之间。平均潜伏期和感染期分别为34（28、39）天和40（23、71）天。如果在50例报告病例后开始对16-65岁人群（不包括未获得疫苗许可的孕妇）进行反应性两剂疫苗接种，可使营地特定死亡率平均降低10%至29%。预先接种两剂疫苗可使死亡率降低35%至65%。如果将覆盖范围扩大到目前未获得疫苗许可的群体，这两种战略都将更加有效。例如，两剂先发制人的疫苗接种，如果扩大到包括孕妇，可使死亡率平均降低66%至82%。结论戊肝病毒在难民营环境中具有很高的传播潜力。预期通过接种疫苗可大幅降低死亡率，即使是反应性接种。如果能够在孕妇中确定疫苗的安全性和有效性，则可能产生更大的影响。资助惠康信托基金（106491/Z/14/Z和089275/Z/09/Z）。BC: MRC/DfID （MR/K006924/1）。
Background Hepatitis E Virus (HEV) is an important cause of morbidity and mortality in emergency and refugee camp settings. Symptomatic infection is associated with case fatality rates of ~20% in pregnant women. However, its epidemiology is poorly understood and the potential impact of immunisation in outbreak settings uncertain. We aimed to estimate key epidemiological parameters for HEV and to evaluate the potential impact of both reactive vaccination (initiated in response to an epidemic) and pre-emptive vaccination. Methods We analysed data from one of the world’s largest recorded HEV epidemics, which occurred in refugee camps in Uganda (2007-2009), using transmission dynamic models to estimate epidemiological parameters and assess the potential impact of reactive and pre-emptive vaccination strategies. Results Under baseline assumptions we estimated the basic reproduction number of HEV to range from 3.9 (95% CrI 2.8, 5.4) to 8.9 (5.4, 14.2). Mean latent and infectious periods were estimated to be 34 (28, 39) and 40 (23, 71) days respectively. Reactive two-dose vaccination of those aged 16-65 years excluding pregnant women (for whom vaccine is not licensed), if initiated after 50 reported cases, led to mean camp-specific reductions in mortality of 10 to 29%. Pre-emptive vaccination with two doses reduced mortality by 35 to 65%. Both strategies were more effective if coverage was extended to groups for whom the vaccine is not currently licensed. For example, two dose pre-emptive vaccination, if extended to include pregnant women, led to mean reductions in mortality of 66 to 82%. Conclusions HEV has a high transmission potential in refugee camp settings. Substantial reductions in mortality through vaccination are expected, even if used reactively. There is potential for greater impact if vaccine safety and effectiveness can be established in pregnant women. Funding Wellcome Trust (106491/Z/14/Z and 089275/Z/09/Z). BC: MRC/DfID (MR/K006924/1).