Effectiveness of an oral cholera vaccine in Zanzibar: findings from a mass vaccination campaign and observational cohort study
Effectiveness of an oral cholera vaccine in Zanzibar: findings from a mass vaccination campaign and observational cohort study
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DOI：
10.1016/s1473-3099(12)70196-2
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发表时间：
2012-11-01
影响因子：
56.3
通讯作者：
Deen, Jacqueline
中科院分区：
文献类型：
--
作者：
Khatib, Ahmed M.;Ali, Mohammad;Deen, Jacqueline
背景自1978年以来，东非的桑给巴尔一直受到霍乱的严重和反复影响。我们评估的有效性，口服霍乱疫苗在高危人群中的群岛，估计间接（牛群）的保护所赋予的疫苗和直接vaccineeffectiveness.Methods我们提供了两个剂量的杀死全细胞B亚单位霍乱疫苗的年龄在2岁及以上的个人在6个农村和城市的网站。为了估计疫苗的直接保护，我们使用具有对数链接函数的广义估计方程，同时控制潜在的混杂变量，比较了接种者和非接种者之间的霍乱发病率。为了估计间接影响，我们使用了地理信息系统方法，并在控制了潜在的混杂变量后，评估了社区一级疫苗覆盖率与该社区未接种疫苗居民霍乱风险之间的关联。这项研究在ClinicalTrials.gov上注册，编号为NCT 00709410。在48178名有资格接种疫苗的人中，23921人（50%）接种了两剂疫苗。2009年2月至2010年5月期间，爆发了霍乱，使我们能够评估疫苗的有效性。在接受两剂疫苗的参与者中，疫苗对霍乱的直接保护率为79%（95% CI 47-92）。间接（群）保护是由一个家庭的邻里内的未接种疫苗的居民霍乱的风险降低，因为在该neighborhood increased.Interpretation的疫苗覆盖率我们的研究结果表明，口服霍乱疫苗提供直接和间接（群）的保护在撒哈拉以南非洲地区的设置。大规模口服霍乱免疫接种运动不仅有可能为接种疫苗的个人提供保护，而且还可以为社区中未接种疫苗的成员提供保护，应大力考虑更广泛地使用。由于这是一种国际许可的疫苗，我们不能进行随机安慰剂对照试验，但疫苗对非霍乱腹泻的有效性的缺乏表明，对霍乱的保护不能用偏倚来解释。
Background Zanzibar, in east Africa, has been severely and repeatedly affected by cholera since 1978. We assessed the effectiveness of oral cholera vaccination in high-risk populations in the archipelago to estimate the indirect (herd) protection conferred by the vaccine and direct vaccine effectiveness.Methods We offered two doses of a killed whole-cell B-subunit cholera vaccine to individuals aged 2 years and older in six rural and urban sites. To estimate vaccine direct protection, we compared the incidence of cholera between recipients and non-recipients using generalised estimating equations with the log link function while controlling for potential confounding variables. To estimate indirect effects, we used a geographic information systems approach and assessed the association between neighbourhood-level vaccine coverage and the risk for cholera in the non-vaccinated residents of that neighbourhood, after controlling for potential confounding variables. This study is registered with ClinicalTrials.gov, number NCT00709410.Findings Of 48 178 individuals eligible to receive the vaccine, 23 921 (50%) received two doses. Between February, 2009, and May, 2010, there was an outbreak of cholera, enabling us to assess vaccine effectiveness. The vaccine conferred 79% (95% CI 47-92) direct protection against cholera in participants who received two doses. Indirect (herd) protection was shown by a decrease in the risk for cholera of non-vaccinated residents within a household's neighbourhood as the vaccine coverage in that neighbourhood increased.Interpretation Our findings suggest that the oral cholera vaccine offers both direct and indirect (herd) protection in a sub-Saharan African setting. Mass oral cholera immunisation campaigns have the potential to provide not only protection for vaccinated individuals but also for the unvaccinated members of the community and should be strongly considered for wider use. Because this is an internationally-licensed vaccine, we could not undertake a randomised placebo-controlled trial, but the absence of vaccine effectiveness against non-cholera diarrhoea indicates that the noted protection against cholera could not be explained by bias.