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

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.