圣地亚哥两项研究发现，即便在霍乱暴发开始后的几周才进行霍乱疫苗的接种，这也可能挽救生命并有助于限制疫情。
 
尽管世界卫生组织目前推荐在暴发中考虑进行免疫接种，它说缺乏证据表明这种“亡羊补牢”式的免疫接种有效果。
 
但是这些新的研究——它们发表在了1月25日出版的《公共科学图书馆·被忽视的热带病》（PLoS Neglected Tropical Diseases）上——首次表明了免疫接种可以在霍乱暴发期间减少病例并挽救生命，这为开始在海地进行免疫接种的呼吁增加了分量。
 
于去年10月开始的海地霍乱暴发是在2010年1月的地震破坏之后出现的，它影响了19万多人，导致将近4000人死亡。
 
其中一项研究估计，在2008年津巴布韦的一场霍乱暴发中，如果迅速地让半数人口接种Dukoral疫苗，至多40%的死亡本可以避免。
 
该研究的作者之一，韩国国际疫苗研究所的研究人员Rita Reyburn说，在这两种情况下，在霍乱暴发前基础设施就崩溃了。
 
Reyburn说，在海地的卫生设施和供水得到大幅度改进之前，“大规模接种口服霍乱疫苗是我们能够提供的最有希望的帮助……它们几乎肯定能够减少未来的病例数量”。
 
但是泛美卫生组织的家庭与社区卫生部门的免疫接种顾问Andrea Vicari说，这些发现并没有改变世界卫生组织的估计。
 
他说，在Reyburn的论文中，在几周之内提供数以百万份的疫苗的估计是不现实的——而且为足够数量的海地人接种需要很长时间，这让它的影响力的效果较小。
 
他说：“可以说海地的暴发比在该论文中建模的津巴布韦霍乱暴发远远更具爆炸性。”
 
第二项研究发现，在2008年越南河内暴发霍乱之后使用ORC-Vax疫苗（在印度得到许可证的这种疫苗的改良版本称为Shanchol）提供了针对霍乱的76%的保护。
 
但是该研究的作者之一、韩国国际疫苗研究所的研究人员Anna Lopez说需要进一步的证据从而让补救性质的免疫接种成为常规，因为该研究受到了样本规模小的限制。
 
“不幸的是，在霍乱暴发期间很难进行研究，因为我们的首要任务是照顾病人。”
 
她说如果在海地进行一场免疫接种运动，“应该规划好适当的交货时间，因为制造商可能需要一段时间才能为一场免疫接种运动提供疫苗”。

推荐原文：

PLoS Negl Trop Dis. doi: 10.1371/journal.pntd.0000952.

The Case for Reactive Mass Oral Cholera Vaccinations

Rita Reyburn,1* Jacqueline L. Deen,1 Rebecca F. Grais,2 Sujit K. Bhattacharya,3 Dipika Sur,3 Anna L. Lopez,1 Mohamed S. Jiddawi,4 John D. Clemens,1 and Lorenz von Seidlein5

Abstract
Introduction
The outbreak of cholera in Zimbabwe intensified interest in the control and prevention of cholera. While there is agreement that safe water, sanitation, and personal hygiene are ideal for the long term control of cholera, there is controversy about the role of newer approaches such as oral cholera vaccines (OCVs). In October 2009 the Strategic Advisory Group of Experts advised the World Health Organization to consider reactive vaccination campaigns in response to large cholera outbreaks. To evaluate the potential benefit of this pivotal change in WHO policy, we used existing data from cholera outbreaks to simulate the number of cholera cases preventable by reactive mass vaccination.
Methods
Datasets of cholera outbreaks from three sites with varying cholera endemicity—Zimbabwe, Kolkata (India), and Zanzibar (Tanzania)—were analysed to estimate the number of cholera cases preventable under differing response times, vaccine coverage, and vaccine doses.

Findings
The large cholera outbreak in Zimbabwe started in mid August 2008 and by July 2009, 98,591 cholera cases had been reported with 4,288 deaths attributed to cholera. If a rapid response had taken place and half of the population had been vaccinated once the first 400 cases had occurred, as many as 34,900 (40%) cholera cases and 1,695 deaths (40%) could have been prevented. In the sites with endemic cholera, Kolkata and Zanzibar, a significant number of cases could have been prevented but the impact would have been less dramatic. A brisk response is required for outbreaks with the majority of cases occurring during the early weeks. Even a delayed response can save a substantial number of cases and deaths in long, drawn-out outbreaks. If circumstances prevent a rapid response there are good reasons to roll out cholera mass vaccination campaigns well into the outbreak. Once a substantial proportion of a population is vaccinated, outbreaks in subsequent years may be reduced if not prevented. A single dose vaccine would be of advantage in short, small outbreaks.

Conclusions
We show that reactive vaccine use can prevent cholera cases and is a rational response to cholera outbreaks in endemic and non-endemic settings. In large and long outbreaks a reactive vaccination with a two-dose vaccine can prevent a substantial proportion of cases. To make mass vaccination campaigns successful, it would be essential to agree when to implement reactive vaccination campaigns and to have a dynamic and determined response team that is familiar with the logistic challenges on standby. Most importantly, the decision makers in donor and recipient countries have to be convinced of the benefit of reactive cholera vaccinations.