Health and economic burden of chikungunya infection and potential benefits of vaccination in 32 countries: a vaccine impact modelling study

Background Chikungunya is an emerging vector-borne disease caused by Alphavirus chikungunya (CHIKV). As the first CHIKV vaccines gain regulatory approval, estimates of their health-economic impact are needed to guide investments and decision-making. Methods We developed a modelling framework comprising a CHIKV environmental suitability map, a serocatalytic model estimating force of infection, and a decision-analytic disease progression model to project the health-economic burden of chikungunya across 32 countries. Societal costs (2023 International dollars) included healthcare use, productivity losses and monetised disability-adjusted life-years (DALYs). We simulated several preventive CHIKV vaccination campaigns, conservatively assuming no impact on transmission. We estimated threshold vaccine costs as the cumulative societal costs averted per vaccine dose. Results From 2025 to 2050, our model projected a cumulative 862 million (95% uncertainty interval: 737 million-1.08 billion) CHIKV infections, 1.95 million (1.62 million-2.49 million) hospitalisations and 66,900 (53,000-88,000) deaths across 32 countries, leading to 7.21 million (5.64 million-9.66 million) DALYs and $106 billion ($72.6 billion-$148 billion) in societal costs. A five-year population-wide campaign reaching 50% of individuals aged 12 years and older, followed by ten years of annual routine adolescent vaccination, averted 881,000 (673,000-1.21 million) DALYs and $16.8 billion ($11.3 billion-$23.9 billion) in societal costs. This strategy was the most cost-efficient, with threshold vaccine costs ranging from $0.30 ($0.14-$0.57) in Chad to $55.5 ($39.4-$78.9) in Panama. Conclusion CHIKV vaccination could substantially reduce the future health and economic burden of chikungunya, supporting its consideration in national and regional immunisation programmes.