Guiding vaccine policy for chikungunya in Brazil: a cost-effectiveness analysis of live-attenuated versus recombinant chikungunya vaccines in Brazilian adults ≥18 years

Objectives: Chikungunya virus (CHIKV) causes substantial burden in Brazil, with 3.2 million cases and US$9.8 billion in costs from 2011 to 2020. This study evaluates the cost-effectiveness of live-attenuated and recombinant vaccines for adults ≥18 years to guide vaccination strategies. Design: A modified Susceptible-Vaccinated-Exposed-Infectious-Recovered-Deceased model was used to evaluate the cost-effectiveness of live-attenuated and recombinant chikungunya vaccines vs no vaccination in a cohort of 1000 Brazilian adults ≥18 years over 10 years. Costs (2025 US dollars, US$/Brazilian reais, R$) and quality-adjusted life-years (QALYs) were estimated from both the Brazilian healthcare sector and societal perspective assuming a 5.00% annual social discount rate. Model inputs were derived from published data, clinical trials and assumptions. Main outcome measures: Incremental cost-effectiveness ratios and incremental net monetary benefits (INMB) were calculated for each vaccine compared with no vaccination. Deterministic and probabilistic sensitivity analyses (PSA) were conducted to assess the impact of parameter uncertainty. Results: In the base case, and from both healthcare sector and societal perspectives, the live-attenuated vaccine was more effective (336 011 QALYs) and less costly (healthcare: US$0.12 million/R$0.68 million; societal: US$2.85 million/R$15.93 million) than the recombinant vaccine (335 787 QALYs; US$0.15 million/R$0.83 million; US$2.88 million/R$16.11 million) or no vaccination (335 472 QALYs; US$0.02 million/R$0.11 million; US$2.76 million/R$15.44 million), thus dominating both. At a societal willingness-to-pay threshold of US$10 306 (R$57 601) per QALY, its INMB was US$5.46 million (R$30.50 million) and US$5.47 million (R$30.58 million) from the healthcare and societal perspectives, respectively, compared with US$3.12 million (R$17.44 million) and US$3.13 million (R$17.49 million) for the recombinant vaccine. PSA and a battery of sensitivity analyses showed the live-attenuated vaccine remained dominant at this threshold. Conclusions: Chikungunya vaccination is a highly cost-effective strategy to reduce the health and economic burden of CHIKV in Brazil, with the live-attenuated vaccine favoured over the recombinant formulation.