ORAL CHOLERA VACCINES: THE W.H.O. VIEW

Wednesday, 24th of August 2011

ORAL CHOLERA VACCINES: THE W.H.O. VIEW

Until the 1990s, only parenterally administered cholera vaccines were available for the prevention of cholera. They were of low efficacy and short duration of protection, and afforded little or no protection against the carrier state. From 1973, WHO removed these vaccines from those listed on the WHO International Vaccination Certificate.

The present century has seen the commercialization of oral cholera vaccines with more satisfactory protection of adults and, especially, children. There is one prequalified cholera vaccine, of Swedish manufacture, listed on the WHO homepage, at http://www.who.int/immunization_standards/vaccine_quality/117_cholera/en/index.html

The package insert (English, French, and Spanish) is at http://www.who.int/immunization_standards/vaccine_quality/117_cholera.pdf

WHO re-issued its position paper on cholera vaccination in 2010, taking into account recent research in the field. The complete text of the position paper, in French and English, is at

http://www.who.int/wer/2010/wer8513.pdf

The following excerpt from the WHO position paper, ‘control of cholera outbreaks, ’ is of special interest to those dealing with epidemics or potential epidemics.

‘The mainstay of control measures to be implemented during ongoing epidemics should remain (i) providing appropriate treatment to people with cholera, (ii) implementing interventions to improve water and sanitation and (iii) mobilizing communities.

‘Pre-emptive vaccination should be considered by local health authorities to help prevent potential outbreaks or the spread of current outbreaks to new areas. Finalizing of predictive risk-assessment tools to help countries determine when pre-emptive cholera vaccination might be used is needed urgently; these tools should be made available and field-tested as soon as possible.

‘Given the recent large and prolonged outbreaks of cholera (for example, in Angola and Zimbabwe), reactive vaccination could be considered by local health authorities as an additional control measure, depending on the local infrastructure and following a thorough investigation of the current and historical epidemiological situation, and clear identification of geographical areas to be targeted.

‘The 3-step decision-making tool developed for crisis situations should guide health authorities in their decisions on whether to use cholera vaccine during complex emergencies. Considering the lack of experience with implementing reactive vaccination against cholera, the feasibility and impact of vaccination in halting ongoing outbreaks should be documented and widely disseminated.

‘Pre-emptive or reactive vaccination should cover as many people as possible who are eligible to receive the vaccine (for example, children aged ≥1 years or ≥2 years, depending on the vaccine), and should be conducted as quickly as possible.’