Prevention and control of cholera outbreaks: WHO policy and recommendations
There are two WHO prequalified oral cholera vaccines (OCV) currently available on the market. These vaccines were proven safe, effective and well accepted and are available for individuals aged one year and above. They are administered in two doses given at least 7 days apart. Overall, more than 1.6 million doses of WHO prequalified OCVs have been deployed in mass vaccination campaigns since 1997. WHO official recommendations for the use of OCV have been issued, and state that:
- OCV should always be used as an additional public health tool and should not replace usually recommended control measures such as improved water supplies, adequate sanitation and health education. It needs also to be linked to strengthened surveillance and early warning.
- Pre-emptive vaccination campaigns with OCV should be used in areas where the disease is endemic, including during humanitarian crises, as an additional means for cholera prevention and control, but should not replace usually recommended control measures such as improved water supply, adequate sanitation, food safety, and health education. In such settings, vaccination should be targeted at high-risk areas and high risk population groups, such as displaced populations in camps with precarious living conditions, underserved populations in resource poor settings, etc.
- Mass vaccination campaigns may be organized on a reactive basis, as part of the response to a cholera outbreak which has already commenced, to reduce mortality and limit the spread of the disease. However, vaccination should not disrupt the provision of other high-priority health interventions to control or prevent cholera. Considering the lack of experience with implementing reactive vaccination against cholera, the feasibility and impact of vaccination in halting on-going outbreaks should be documented and results widely disseminated.
The use of the parenteral cholera vaccine has never been recommended by WHO due to its low protective efficacy and the high occurrence of severe adverse reactions.