Targeted Vaccination of Children in Urban Slums Against Cholera: Evaluation of a Potentially Cost-effective and Impactful Strategy for Deploying Oral Cholera Vaccine in Bangladesh

Burden: Cholera remains a major global problem, resulting in more than 100,000 deaths and several million cases annually , mostly children. Vaccination has been reconsidered as a key component of the public health response to cholera. Bangladesh has one of the world's highest burdens of endemic cholera, with an estimated 300,000 cholera cases and over 4,500 deaths annually, and with high caseloads and frequent outbreaks in more than half of the country. The endemicity of cholera in Bangladesh is demonstrated by the predictable yearly occurrence of the disease in the country's high-risk districts and the repetitive seasonal pattern of cholera outbreaks, either in spring or autumn, or both .

Knowledge gap: More evidence is needed to address uncertainties around the cholera disease burden, as well as the impact, feasibility, and cost-effectiveness of various vaccination strategies against cholera, to add to the existing knowledge base. A special need for acquiring field evidence of these vaccine attributes in settings with endemic cholera, which account for a very large fraction of the global cholera disease burden, is also recognized .

Relevance: Nonetheless, the assertion that selective vaccination of children with OCV is an impactful approach to controlling cholera at the population level rests on unproven assumptions, since there are no studies that directly address this vaccination strategy. Therefore, further study on whether targeted mass immunization can create efficiencies that general mass immunization would not, is warranted. The Investigators therefore believe that the most compelling question for the control of endemic cholera in Bangladesh is how targeting 1-14 year olds in urban slums, using the established platform of targeted mass childhood immunization recently deployed by the GOB for measles-rubella (MR) vaccine, impacts on the overall burden of cholera in the population and how feasible and cost-effective this strategy is. Addressing these questions will add to the evidence base on the most cost efficient and effective settings and strategies for use of OCV to control endemic disease and optimize health impact.

Hypothesis : Vaccination of children under 15 years of age in urban slums of Dhaka will confer at least 50% overall protection to the entire population through combined direct and indirect protective effects and it will be cost effective.

Objectives:To evaluate the feasibility, efficiency, and impact of a two-dose regimen of the oral cholera vaccine (OCV) Shanchol delivered to children aged 1-14 years residing in urban slums, leveraging a targeted mass immunization delivery platform used for other vaccines in Bangladesh.