OBJECTIVES: Chikungunya virus (CHIKV) poses significant health risks in endemic regions such as Puerto Rico. The live attenuated chikungunya vaccine, IXCHIQ, has shown promise in preventing CHIKV. This study evaluates the cost-effectiveness of vaccinating Puerto Rican adults aged 18 and above with IXCHIQ compared to no vaccination. The objective was to determine whether the IXCHIQ vaccine should be recommended for routine vaccination of adults aged ≥18 years, considering past CHIKV outbreaks and the risk of outbreak recurrence.

METHODS: A cost-effectiveness analysis was conducted using a societal perspective, encompassing all relevant medical and non-medical costs, including patient time, caregiver time, transportation, and productivity losses. A healthcare system perspective was also examined in sensitivity analyses. It was assumed that an outbreak could recur within the next 20 years, with the risk distributed stochastically over this 20-year period in the model. The economic evaluation compared a no-vaccination strategy with a hypothetical IXCHIQ vaccination strategy in a population aged ≥18 years.

RESULTS: For adults aged ≥18 years, the incremental cost-effectiveness ratio (ICER) was $4,859 per quality-adjusted life year (QALY) gained from a societal perspective. The number needed to vaccinate to prevent one CHIKV case was 5.73. The hypothetical strategy demonstrated significant reductions in CHIKV cases, hospitalizations, and fatalities, with overall cost savings in medical and non-medical costs despite the additional vaccination expense. Sensitivity analyses confirmed the robustness of the model, consistently showing positive outcomes across various scenarios and perspectives, including the healthcare perspective.

CONCLUSIONS: The IXCHIQ vaccination program is cost-effective for adults aged ≥18 years in Puerto Rico, when assessing the likelihood of an outbreak within the next 20 years. The findings support recommending the IXCHIQ vaccine to mitigate the public health impact of CHIKV in this population, with robust results confirmed across multiple analyses.