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.
复制标题
DOI：
10.1371/journal.pntd.0006807
复制
发表时间：
2018-09
影响因子：
3.8
通讯作者：
Siddiqui R
中科院分区：
文献类型：
--
作者：
Cooper BS;White LJ;Siddiqui R
戊型肝炎病毒（HEV）是全球急性病毒性肝炎的主要原因。有症状感染与约20%的孕妇病死率有关，据估计，仅在南亚，每年就有约10，000例与妊娠有关的死亡。最近，苏丹、乌干达和南苏丹的流离失所者营地发生了大规模、有充分记录的疫情，死亡率很高。然而，戊型肝炎的流行病学定义不明确，不同的免疫策略在疫情环境中的价值不确定。我们的目的是估计戊型肝炎病毒的关键流行病学参数，并评估反应性疫苗接种（在应对流行病开始）和先发制人的疫苗接种的潜在影响。我们分析了发生在乌干达境内流离失所者营地（2007-2009年）的世界上最大的HEV流行病之一的数据，使用传播动态模型估计流行病学参数，并评估反应性和先发制人的疫苗接种策略的潜在影响。在基线假设下，我们估计三个独立营地的HEV基本繁殖数范围为3.7（95%可信区间[CrI] 2.8，5.1）至8.5（5.3，11.4）。平均潜伏期和感染期估计分别为34（95%CrI 28，39）和40（95%CrI 23，71）天。假设疫苗覆盖率为90%，对16-65岁人群（不包括孕妇（其疫苗未获得许可））进行反应性两剂疫苗接种，如果在50例报告病例后开始接种，则导致营地特异性死亡率平均降低10%至29%。两剂预防接种可将死亡率降低35%至65%。如果将覆盖范围扩大到目前尚未获得疫苗许可的群体，这两种策略都更有效。例如，两剂预防性疫苗接种，如果扩大到包括孕妇，导致死亡率平均降低66%至82%。戊型肝炎病毒在流离失所的人群中传播的可能性很高。通过接种疫苗，即使是反应性使用，预计死亡率也会大幅降低。如果能够在孕妇中确定疫苗的安全性和有效性，则有可能产生更大的影响。戊型肝炎病毒是发展中国家急性病毒性肝炎的主要原因。约20%的感染者出现临床症状;其中约2%的非妊娠病例和20%的妊娠病例死亡。在中国，有一种安全有效的戊型肝炎疫苗已被批准用于16-65岁未怀孕的人群。在暴发环境中使用这种疫苗的可能性以前没有被检查过。我们分析了世界上最大的HEV流行病之一的数据。我们估计，在流行病开始时，一个病例平均感染4到9个其他人。我们发现，仅限于16-65岁未怀孕的人群接种疫苗，如果反应性使用（在疫情开始后开始接种疫苗），可以将疫情环境中的死亡率降低约10%至30%;同一群体的先发制人接种可以将死亡率降低35%至65%。如果疫苗接种能够安全地扩大到孕妇和其他年龄组而不丧失效力，死亡率就有可能大幅降低。然而，即使这是可能的，反应性疫苗接种也不太可能将死亡率降低50%以上，而先发制人的疫苗接种可以将死亡率降低80%至100%。
Hepatitis E Virus (HEV) is the leading cause of acute viral hepatitis globally. Symptomatic infection is associated with case fatality rates of ~20% in pregnant women and it is estimated to account for ~10,000 annual pregnancy-related deaths in southern Asia alone. Recently, large and well-documented outbreaks with high mortality have occurred in displaced population camps in Sudan, Uganda and South Sudan. However, the epidemiology of HEV is poorly defined, and the value of different immunisation strategies in outbreak settings uncertain. We aimed to estimate the critical epidemiological parameters for HEV and to evaluate the potential impact of both reactive vaccination (initiated in response to an epidemic) and pre-emptive vaccination. We analysed data from one of the world's largest recorded HEV epidemics, which occurred in internally-displaced persons 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. Under baseline assumptions we estimated the basic reproduction number of HEV in three separate camps to range from 3.7 (95% Credible Interval [CrI] 2.8, 5.1) to 8.5 (5.3, 11.4). Mean latent and infectious periods were estimated to be 34 (95% CrI 28, 39) and 40 (95% CrI 23, 71) days respectively. Assuming 90% vaccine coverage, 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%. HEV has a high transmission potential in displaced population 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. Hepatitis E virus is a leading cause of acute viral hepatitis in developing countries. About 20% of those infected develop clinical symptoms; of those, about 2% of non-pregnant cases and 20% of pregnant cases die. There is a safe and effective HEV vaccine that is licensed in China for those aged 16–65 years who are not pregnant. The potential for using this vaccine in outbreak settings has not previously been examined. We analysed data from one of the world’s largest recorded HEV epidemics. We estimated that one case infects, on average, between 4 and 9 others at the start of an epidemic. We found that vaccination restricted to those aged 16–65 who are not pregnant could reduce mortality in outbreak settings by between about 10 and 30% if used reactively (initiating vaccination after the start of an epidemic); pre-emptive vaccination of the same group could reduce mortality by 35–65%. Substantially higher reductions in mortality are likely if vaccination can be safely extended to pregnant women and other age groups without loss of effectiveness. However, even if this is possible, reactive vaccination is unlikely to reduce mortality by more than 50% while pre-emptive vaccination can reduce mortality by 80 to 100%.
登录
查看更多内容
影响因子：
3.7
作者：
Amanya G;Kizito S;Nabukenya I;Kalyango J;Atuheire C;Nansumba H;Abwoye SA;Opio DN;Kibuuka E;Karamagi C
通讯作者：
Karamagi C
DOI：
10.1097/ede.0b013e3182572581
发表时间：
2012-07
期刊：
Epidemiology (Cambridge, Mass.)
影响因子：
--
作者：
Grad YH;Miller JC;Lipsitch M
通讯作者：
Lipsitch M
影响因子：
4.8
作者：
Chandra NS;Sharma A;Malhotra B;Rai RR
通讯作者：
Rai RR
影响因子：
11.8
作者：
Boccia, Delia;Guthmann, Jean-Paul;Guerin, Philippe Jean
通讯作者：
Guerin, Philippe Jean
影响因子：
3.7
作者：
Nannyonga, Betty;Sumpter, David J. T.;Luboobi, Livingstone S.
通讯作者：
Luboobi, Livingstone S.