OBJECTIVES: Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infection (LRTI) in young children and poses a significant burden for Brazil's public healthcare system (SUS). Palivizumab is the sole preventive intervention for early preterm infants (<29 weeks), or those with comorbidities. Nirsevimab is a monoclonal antibody with an extended half-life which has 70-80% efficacy for the prevention of RSV-LRTI in broad infant populations, regardless of gestational age. This study aims to model RSV-related hospitalizations and costs of the impact of nirsevimab on SUS population, compared to Standard of Practice (SoP).

METHODS: A decision analytic model was developed to estimate RSV-LRTI events in a Brazilian birth cohort during their first year of life. Parameters were derived from published literature and Brazilian open-source databases (SIH-SUS and SINASC). We estimated 2,182,446 children would be <12 months in 2024, of which 0.84% would be eligible for palivizumab, 10.45% would be late preterm (29-36 weeks) and 88.71% term infants. We assumed a 70% prophylaxis coverage rate with nirsevimab.

RESULTS: Estimates for RSV-related hospitalizations under SoP are 658 for palivizumab eligible, 9,097 for late preterm, and 42,837 for term infants, including 5,144 hospitalizations in pediatric intensive care units (PICU). In the modeled scenario, nirsevimab would have prevented 18,484 hospitalizations (94, 3,221 and 15,169 for palivizumab eligible, preterm and term infants, respectively) including 1,866 PICU hospitalizations. Estimated savings by preventing these hospitalizations are BRL 53.8 million (BRL 0.35 million, 10.9 million and 42.6 million for palivizumab eligible, preterm, and term infants, respectively, not accounting for outpatients’ care and social costs.

CONCLUSIONS: Our findings indicates that nirsevimab could substantially reduce RSV-related hospitalization burden and costs. This study offers valuable information for policymakers evaluating the benefits of nirsevimab coverage in SUS for RSV prophylaxis.