
Three-year-old Salomon looks on as he undergoes treatment for cholera at the general hospital in Minova. Photo: Arjun Claire
On April 25-27, 2017, the World Health Organization (WHO) Strategic Advisory Group of Experts (SAGE) on vaccines and immunization took up oral cholera vaccination during its meeting, with a view of updating the 2010 WHO position paper [1]. WHO regularly releases position papers to guide member states on vaccines and immunization that have global public health importance.
Provisions for safe water, improved sanitation and hygiene (WASH) as well as appropriate clinical case management have been the mainstays of cholera control. WHO’s position on oral cholera vaccine (OCVs) use has evolved over the years. In the first cholera vaccine position paper in 2001, the WHO solely recommended the pre-emptive use of OCV in high-risk populations [2]. This was further complicated with WHO’s position in 2005, that, “the current internationally-available pre-qualified vaccine (Dukoral) is not recommended once an outbreak of cholera has started” [3]. As cholera outbreaks became prolonged and protracted, such as in Zimbabwe and Angola, and with the availability of a new vaccine (Shanchol) in 2010, the WHO released a recommendation, “to consider the use of oral cholera vaccines in reactive situations” (i.e., when an outbreak has already begun) [4].
However, since the release of the 2010 position paper, cholera cases persisted, affecting countries that have not seen cholera for many years. In 2013, an OCV stockpile was created that has since released almost 13 million doses of OCV for use in mass campaigns in diverse settings, such as humanitarian emergencies, outbreaks, and areas with endemic cholera [5].
Experiences from these campaigns have shown that a two-dose OCV schedule is safe, feasible, acceptable and effective in all settings. A single dose of the vaccine was also shown to be efficacious for six months in a study in a cholera-endemic setting [6]. Additionally, studies among pregnant women have shown the vaccine to be safe [7].
With an accumulating body of evidence on OCV use, and increasing OCV supply by licensure of yet another vaccine in December 2015 (Euvichol), a revised set of recommendations is expected from the WHO SAGE. It is anticipated that the new position paper will provide concrete guidance on the use of OCV not only in endemic areas but during humanitarian crises and in times of outbreaks as well [1]. This will clarify the role of OCV in cholera control and hopefully stop the misconceptions and misunderstandings on OCV use and implementation, particularly in countries where OCVs are most needed.
References:
[1] WHO. Meeting of the Strategic Advisory Group of Experts on immunization, April 2017 - conclusions and recommendations. Releve epidemiologique hebdomadaire / Section d'hygiene du Secretariat de la Societe des Nations = Weekly epidemiological record / Health Section of the Secretariat of the League of Nations. 2017;92:301-20
[2] WHO. Cholera vaccines. Releve epidemiologique hebdomadaire / Section d'hygiene du Secretariat de la Societe des Nations = Weekly epidemiological record / Health Section of the Secretariat of the League of Nations. 2001;76:117-24.
[3] Chaignat CL, Monti V. Use of oral cholera vaccine in complex emergencies: what next? Summary report of an expert meeting and recommendations of WHO. Journal of health, population, and nutrition. 2007;25:244-61.
[4] WHO. Cholera vaccines: WHO position paper. Releve epidemiologique hebdomadaire / Section d'hygiene du Secretariat de la Societe des Nations = Weekly epidemiological record / Health Section of the Secretariat of the League of Nations. 2010;85:117-28.
[5] WHO. Deployments from the oral cholera vaccine stockpile, 2013-2017. Releve epidemiologique hebdomadaire / Section d'hygiene du Secretariat de la Societe des Nations = Weekly epidemiological record / Health Section of the Secretariat of the League of Nations. 2017;92:437-42.
[6] Azman, AS et al. Effectiveness of one dose of oral cholera vaccine in response to an outbreak: a case-cohort study. The Lancet: Global Health. 2016; 10.1016/S2214-109X(16)30211-X
[7] Mohammad Ali et al. Safety of a killed oral cholera vaccine (Shanchol) in pregnant women in Malawi: an observational cohort study. The Lancet: Infectious Disease. 2017; 10.1016/S1473-3099(16)30523-0