Cholera vaccination: How and when to use it

Abstract

After nearly three decades of research with killed oral cholera vaccine (OCV), in 2010 the World Health Organization revised recommendations regarding the use of OCV to state,1 “Given the availability of two oral cholera vaccines and data on their efficacy, field effectiveness, feasibility and acceptance in cholera-affected populations, immunization with these vaccines should be used in conjunction with other prevention and control strategies in areas where the disease is endemic and should be considered in areas at risk for outbreaks.” Then in 2013 an OCV stockpile was developed (http://www.who.int/cholera/vaccines/ocv_stockpile_2013/en/), and GAVI decided to provide additional funding for OCV. Clearly OCV is now one of the tools to be used for controlling cholera. When OCV is provided to vulnerable people without safe water who often also lack medical care, OCV becomes a lifesaving vaccine. Still there continues to be uncertainty in knowing when and where to implement OCV campaigns. Even if funds were available to pay for the vaccine (3.70 USD/immunized person), the available supply is limited. Thus, the international community is now learning how and when to use OCV and how to integrate it with other cholera control interventions. Some lessons are however becoming clear. The vaccine is safe and acceptable; it lowers the risk of cholera by about 65-70%; protection continues for 3 to 5 years; and when coverage is high, it induces herd protection. In addition, when incidence is high (>1/1000), it is likely to be cost effective and potentially cost saving. Currently, the stockpile targets use of the vaccine to emergency situations, such as unexpected epidemics, where there is hope that the rapid use of vaccine can abort the outbreak. However, computer models clearly demonstrate that OCV can reduce cholera's burden in endemic areas with predictable cholera seasons. The specific strategies for its use, age groups to target, and precise methods for OCV campaigns are still being evaluated. This presentation will discuss the different scenarios when OCV might be considered and will provide a framework for understanding when and where OCV will be especially beneficial. Additional guidance for use of OCV is found at www.stopcholera.org and http://www.who.int/cholera/vaccines/ocv_stockpile_2013/en/.