The impact of geographic targeting of oral cholera vaccination in sub-Saharan Africa: a modeling study

Abstract

Background In May 2018, the World Health Assembly committed to reducing worldwide cholera deaths by 90% by 2030. Oral cholera vaccine (OCV) plays a key role in reducing the near-term risk of cholera, although global supplies are limited. Characterizing the potential impact and cost-effectiveness of mass OCV deployment strategies is critical for setting expectations and developing cholera control plans that maximize chances of success. Methods We compared the projected impacts of vaccination campaigns across sub-Saharan Africa from 2018 through 2030 when targeting geographically according to historical cholera burden and risk factors. We assessed the number of averted cases, deaths, disability-adjusted life-years, and cost-effectiveness with models that account for direct and indirect vaccine effects and population projections over time. Findings Under current vaccine supply projections, an approach that balances logistical feasibility with targeting historical burden is projected to avert 620,000 cases cumulatively (9-26% of cases annually). Targeting by access to improved water and sanitation prevents one-half to one-seventh as many cases as targeting by burden. We find that effective geographic targeting of OCV campaigns can have a greater impact on cost-effectiveness than improvements to vaccine efficacy and moderate increases in coverage. Conclusions Oral cholera vaccines must be targeted strategically in order for campaigns to be cost-effective and impactful. While OCV campaigns will improve cholera control in the near-term, we need a greater supply of vaccines and rapid progress in developing safely managed water and sanitation services in order to achieve the 2030 goals.