Comparative Analysis of Reported Adverse Events with Nirsevimab and Palivizumab in the FAERS Database

Respiratory syncytial virus (RSV) remains a leading cause of hospitalization among infants. Palivizumab has long been used for RSV prophylaxis in high-risk infants, whereas nirsevimab is a newer long-acting monoclonal antibody approved for broader use. Although clinical trials have demonstrated comparable safety profiles, comparative post-marketing safety data remain limited. Authors of this study compared reported adverse events associated with palivizumab and nirsevimab using the FDA Adverse Event Reporting System (FAERS).

A retrospective cross-sectional pharmacovigilance study was conducted using FAERS reports. Adverse events were classified according to the Medical Dictionary for Regulatory Activities (Med-DRA) System Organ Classes. Comparative analyses were performed using chi-square tests and binary logistic regression, with palivizumab as the reference group. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported.

A total of 2,021 reports met the inclusion criteria, including 1,380 for palivizumab and 641 for nirsevimab. Compared with palivizumab reports, nirsevimab reports had higher odds of including injury, poisoning, and procedural complications (OR, 7.55; 95% CI, 5.57-10.35) and skin and subcutaneous tissue disorders (OR, 2.55; 95% CI, 1.51-4.33). Nirsevimab reports had lower odds of including infections and infestations (OR, 0.51; 95% CI, 0.40-0.65), gastrointestinal disorders (OR, 0.29; 95% CI, 0.15-0.52), investigations (OR, 0.37; 95% CI, 0.18-0.68), and respiratory, thoracic, and mediastinal disorders (OR, 0.64; 95% CI, 0.51-0.80).

Nirsevimab and palivizumab demonstrated distinct post-marketing adverse event reporting patterns. Continued post-marketing surveillance is warranted to further characterize the safety profiles of both agents.