A health-economic assessment of the impact of different RSVpreF maternal vaccine strategies to prevent RSV infections among young infants, in France: EPIPACT.
OBJECTIVES Most of the clinical and economic burden of the respiratory syncytial virus (RSV) in pediatric populations is concentrated among infants aged <1 year. Since 2024, RSVpreF vaccine is available in France for the vaccination of pregnant women between 32 and 36 weeks of gestational age, from September to January. This study aimed to model the impact of alternative RSVpreF national vaccination strategies on RSV hospital burden. METHODS A three-state Markov model - Susceptible to be infected, RSV-related hospitalization, and Death - was developed to assess the number of hospitalizations avoided by alternative vaccination strategies. The model population of 627,499 unique births in one year was split in two cohorts of infants born to vaccinated and unvaccinated women. Four strategies were modeled: no vaccination, vaccination between September and January (recommended), between May and January (extended), and year-round. Results were presented at a population level using a healthcare perspective, as cost per hospitalization avoided, and number needed to vaccinate (NNV). RESULTS In the absence of vaccination, 38,625 RSV-related hospitalization among infants under 1 year of age were estimated annually, costing €120.0 million. Compared to no vaccination, the recommended strategy prevented 7,620 (-19.7%) RSV-related hospitalizations, 90.4% of them involved infants aged <3 months (99.5% aged <6 months). The related total cost was €126.4 million, corresponding to cost of €844 per hospitalization avoided, and an NNV of 21 vaccinations to avoid one hospitalization. Compared to the recommended strategy, the extended strategy avoided an additional 4,111 (-13.3%) hospitalizations, 42.0% of them involving infants aged <3 months (95.0% aged <6 months). The total cost of this strategy was €134.4 million (+6.3%), corresponding to a cost of €1,929 per additional hospitalization avoided. Total cost of the year-round strategy was €156.2 million, for 1,306 additional hospitalizations avoided. CONCLUSIONS This is the first cost-effectiveness model to describe the public health impact of alternative vaccination strategies for RSV prevention in France. The number of hospitalizations avoided ranged from 7,600 stays in the recommended strategy, to more than 13,000 in the year-round strategy, corresponding to hospital savings between €24.7 million and €41.5 million. Alternative scenarios were shown to extend prevention to older age groups. Broader vaccination strategies, notably the extended strategy, had a positive impact on RSV hospital burden, with a limited impact on total costs.