Efficacy and safety of nirsevimab for preventing respiratory syncytial virus infection in infants: an updated systematic review and meta-analysis encompassing 11,001 participants.

Background: Respiratory syncytial virus (RSV) is recognized as the leading cause of lower respiratory tract infections (LRTI) and a major contributor to newborn hospitalizations. Recent clinical trials have demonstrated the effectiveness of nirsevimab in preventing RSV infections among infants. This meta-analysis evaluated the efficacy and safety of nirsevimab in healthy infants born at varying gestational ages during their first RSV season.

Methods: Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched electronic databases-PubMed, SCOPUS, Cochrane Library, and Web of Science-to identify relevant studies published up to March 2025.

Results: We included three studies with 11,001 participants. Nirsevimab was significantly associated with decreased hospitalization for LRTI due to RSV (risk ratio [RR]: 0.21; 95% confidence interval [CI] 0.13, 0.33; P = 0.00001), hospitalization for respiratory illness due to any cause (RR: 0.46; 95% CI 0.36, 0.59; P = 0.00001), and medically attended RSV-associated LRTI (RR: 0.25; 95% CI 0.18, 0.36; P = 0.00001) compared to placebo. Comparable results were found in composite safety outcomes and adverse events; however, nirsevimab significantly reduced the incidence of bronchiolitis (RR: 0.70; 95% CI 0.56, 0.88; P = 0.002).

Conclusion: Nirsevimab shows promise in preventing RSV infections and hospitalizations, warranting further study on its practicality and cost-effectiveness.