Academic journal article Bulletin of the World Health Organization

Post-Licensure Deployment of Oral Cholera Vaccines: A Systematic Review/ Deploiement Apres Homologation Des Vaccins Oraux Contre le Cholera: Une Revue systematique/Utilizacion De Vacunas Orales Contra El Colera Posterior a la Aprobacion De Su Uso: Una Revision Sistematica

Academic journal article Bulletin of the World Health Organization

Post-Licensure Deployment of Oral Cholera Vaccines: A Systematic Review/ Deploiement Apres Homologation Des Vaccins Oraux Contre le Cholera: Une Revue systematique/Utilizacion De Vacunas Orales Contra El Colera Posterior a la Aprobacion De Su Uso: Una Revision Sistematica

Article excerpt

Introduction

Vibrio cholerae O1 and O139 causes severe diarrhoea and the main strategies to prevent the disease are to promote hygiene and to ensure safe water and sanitation. These basic needs are often not met in endemic areas with seasonal cholera outbreaks or during man-made or natural disasters in impoverished areas. An additional tool for cholera prevention and control is the oral cholera vaccine. In October 2009, the World Health Organization (WHO) Strategic Advisory Group of Experts on immunization recommended that oral cholera vaccination should be considered as a reactive strategy during outbreaks, in addition to the already recommended preventive use of oral cholera vaccine in endemic areas. (1) A vaccine stockpile was created in 2012, with an initial two million doses to be available mainly for epidemic response in low-income countries. (2) In November 2013, the global alliance for vaccines and immunizations (Gavi Alliance) approved a financial contribution towards the stockpile to expand its use. With the availability of the oral cholera vaccine stockpile, more governments might consider cholera vaccination where needed.

A monovalent inactivated vaccine containing killed whole-cells of V. cholerae serogroup O1 and the B-subunit of cholera toxin was the first oral cholera vaccine to obtain international licensure in 1991 and WHO prequalification in 2001. The vaccine is marketed as Dukoral [R] (Crucell, Netherlands). Randomized, placebo-controlled trials of earlier versions of Dukoral[R] in Bangladesh and the current recombinant B-subunit whole cell vaccine in Peru showed that the vaccine is safe and confers an initial protection of approximately 85% in the first months. (3,4) Follow-up studies in Bangladesh estimated a 62% protection during the first year, 57% during the second year and negligible thereafter. (3)

During the mid-1980s, the National Institute of Hygiene and Epidemiology in Viet Nam developed an oral cholera vaccine for the country's public health programme. A two-dose regimen of a first-generation of monovalent (anti-O1) cholera vaccine had an estimated efficacy of 66% against the El Tor strain of V. cholerae. (5) In 1997, the vaccine was augmented with killed V. cholerae serogroup O139 whole cells to create a bivalent vaccine, (6) which was locally licensed as ORC-Vax[TM] (Vabiotech, Viet Nam). After changing production procedures in 2009, the vaccine was reformulated and licensed as mORC-Vax[TM] (Vabiotech, Viet Nam) and is currently used in Viet Nam's public health programme. (7) However, the vaccine is not pre-qualified by WHO.

To make the mORC-Vax[TM] internationally available, manufacture of the reformulated vaccine was transferred to Shantha Biotechnics Ltd in India, where the national regulatory authority is approved by WHO. (8) This led to the development of Shanchol[TM], which is the third currently-available oral cholera vaccine. A randomized, placebo-controlled trial in India showed that Shanchol[TM] is safe and confers 67% protective efficacy against cholera within two years of vaccination, (8) 66% at three years (9) and 65% at five years (10) of follow-up. Shanchol[TM] was licensed in India in 2009 and received WHO pre-qualification in 2011.

A comparison of the three oral cholera vaccines is shown in Table 1. (11,12) The safety, relative effectiveness and duration of protection of the different types of oral cholera vaccine has previously been reviewed. (13) Here we conduct a systematic review of post-licensure oral cholera vaccines. The objective of the review is to generate information--by describing and analysing the campaigns--that can be used to inform planning for the future use of these vaccines.

Methods

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We searched the Cochrane database of systematic reviews and its database of abstracts and reviews of effects from 1990 to the present and found no reviews of oral cholera vaccination campaigns. …

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