OBJECTIVES: In France, mRNA COVID19 vaccines are recommended for those most at risk of severe outcomes, including immunocompromised individuals (IC). During December 2021 - May 2022, 43% of patients hospitalized in critical care for Omicron were IC. A recent systematic review and meta-analysis in IC found the Moderna vaccine more effective compared with the Pfizer-BioNTech vaccine (RR 0.87 infections, 0.83 hospitalizations, 0.62 deaths). The study objective was to compare the impact of boosting IC with the Moderna vaccine compared with the Pfizer-BioNTech vaccine during France’s Fall 2023 vaccination campaign.

METHODS: A decision-analytic model was used to predict the clinical and economic outcomes of boosting IC in Fall 2023 over a one-year time horizon. The model considers residual protection from prior vaccination, natural infection and Fall 2023 booster vaccine effectiveness (VE). Consequences of infection and associated costs were calculated.

RESULTS: Compared with the Pfizer-BioNTech vaccine, vaccinating the entire IC population with the Moderna vaccine could prevent an additional 158 hospitalizations, 30 deaths and 979 cases of long-COVID, corresponding to 387 quality-adjusted life years (QALYs) prevented, and 1.7M€ in direct medical costs saved to the French healthcare system (or 7.50€ saved per dose of Moderna vaccine administered compared with the Pfizer-BioNTech vaccine). From the societal perspective, 13.9M€ could be saved (or 60.24€ saved per dose of Moderna vaccine administered). Scenario analyses exploring the uncertainty around the COVID-19 incidence and hospitalization rates confirmed the robustness of these findings.

CONCLUSIONS: Vaccinating the entire French IC population (n=230,000) with the Moderna vaccine in Fall 2023 is expected to prevent more cases of COVID-19 related hospitalizations, deaths, and long-COVID compared with vaccinating with the Pfizer-BioNTech mRNA vaccine.