An evaluation was conducted to predict the economic and clinical burden of vaccinating all immunocompromised (IC) individuals aged ≥30 years with mRNA-1273 variant-adapted COVID-19 vaccines versus BNT162b2 variant-adapted vaccines in Fall 2023 and Spring 2024 in France. The number of symptomatic SARS-CoV-2 infections, hospitalizations or deaths due to COVID-19, and long COVID cases, costs and quality-adjusted life years (QALYs) were estimated using a static decision-analytic model. Predicted vaccine effectiveness (VE) were based on real-world data from the original and BA.4/5 variant-adapted vaccines, suggesting higher protection against infection and hospitalization with mRNA-1273 vaccines. VE estimates were combined with COVID-19 incidence and probability of COVID-19 severe outcomes. Uncertainty surrounding VE, vaccine coverage, infection incidence, hospitalization and mortality rates, costs and QALYs were evaluated in sensitivity analyses. In an ideal situation where 100% coverage is achieved, the mRNA-1273 variant-adapted vaccine is predicted to prevent an additional 3,882 infections, 357 hospitalizations, 81 deaths, and 326 long COVID cases when compared to BNT162b2 variant-adapted vaccines in 230,000 IC individuals. This translates to €10.1 million cost-savings from a societal perspective and 645 QALYs gained. Results were consistent across all analyses and most sensitive to variations surrounding VE and coverage. These findings highlight the importance of increasing vaccine coverage, and ability to induce higher levels of protection with mRNA-1273 formulations in this vulnerable population.