Modeling the Potential Public Health and Economic Impact of Nirsevimab Introduction Using Real-World Data in the United States, Spain, and France

OBJECTIVES: Nirsevimab is a long-acting monoclonal antibody indicated for the prevention of respiratory syncytial virus (RSV) related lower respiratory tract infection (LRTI). Following nirsevimab introduction in 2023/2024 RSV season, real-world effectiveness and safety data from several countries, including the United States (US), Spain (SP) and France (FR), has become available. This study aims to evaluate the potential impact of nirsevimab introduction on RSV-related healthcare events and their associated costs, utilizing real-world findings.

METHODS: A static decision analytic model was used to estimate health and cost outcomes associated with RSV following nirsevimab immunization of all infants entering their first RSV season in each country compared to standard of practice, palivizumab restricted to high-risk infants. Health outcomes included medically attended LRTI (hospitalizations, emergency room and primary care visits). We used real-world data for nirsevimab effectiveness in reducing RSV-related hospitalizations (90% effectiveness in the US, 82% in Spain, and 83% in France). For the prevention of RSV-outpatient events, we used efficacies from MELODY and Phase IIb clinical trials and an assumed non-inferior efficacy of nirsevimab versus palivizumab in high-risk infants.

RESULTS: Using real-world effectiveness, we estimated that nirsevimab could reduce the number of RSV-related hospitalizations by 61% in the US, 65% in Spain, and 70% in France, leading to a decrease in associated costs (56% [US], 64% [SP], 69% [FR]). Overall, this could also be translated into a reduction in the number of medically attended LRTI (53% [US], 61% [SP], 64% [FR]) and associated costs (55% [US], 63% [SP], 69% [FR]).

CONCLUSIONS: The potential public health and economic impact of nirsevimab using real world evidence data is significant and consistent with results using efficacies from clinical studies. This analysis reinforces the value of nirsevimab immunization in RSV prevention, highlighting the importance of real-world evidence generation to represent more accurately the prophylaxis value.