COMPARATIVE POST-MARKETING SAFETY STUDY OF NIRSEVIMAB AND PALIVIZUMAB: A PHARMACOVIGILANCE ANALYSIS USING FAERS AND WHO VIGIACCESS
Author(s)
nipa chowdhury, MS1, Mohammad Al-Mamun, PhD2;
1West Virginia University, School of Pharmacy, Morgantown, WV, USA, 2Binghamton University, Systems Science and Industrial Engineering, Binghamton, NY, USA
1West Virginia University, School of Pharmacy, Morgantown, WV, USA, 2Binghamton University, Systems Science and Industrial Engineering, Binghamton, NY, USA
OBJECTIVES: Respiratory syncytial virus (RSV) is a major cause of respiratory tract infection leading to 58,000 to 80,000 hospitalizations in the United States annually for children under 5. Palivizumab was the only RSV prophylaxis until 2023, when nirsevimab became available. This study aims to evaluate and compare the post-marketing safety profiles of nirsevimab and palivizumab using the Food and Drug Administration Adverse Event Reporting System (FAERS) and WHO VigiAccess databases.
METHODS: We extracted adverse event reports from the FAERS and WHO VigiAccess databases from 2023 to 2025 and conducted signal detection using the Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Empirical Bayesian Geometric Mean (EBGM) methods.
RESULTS: FAERS analysis identified 74 signals for nirsevimab and 91 signals for palivizumab. WHO-VigiAccess included 1,279 reports for nirsevimab and 22,290 reports for palivizumab. At the System Organ Classes (SOCs) level, both databases showed a similar distribution, with the most frequently reported categories including infections and infestations; respiratory, thoracic, and mediastinal disorders; and general disorders and administration site conditions. In FAERS, the preferred terms (PTs) with the highest signal intensity for nirsevimab were vaccination error (n= 5; ROR = 42,159.79; EBGM = 3,495.36) and RSV bronchiolitis (n = 222; ROR = 24,041.95; EBGM = 3,173.56). For palivizumab, the strongest signals were Subglottic laryngitis (n = 4; ROR = 1,230.46; EBGM = 682.96) and Bronchiolitis (n = 170; ROR = 524.84; EBGM = 371.59). Only a few events in either database align with FDA-approved labeling, such as rash with nirsevimab and severe thrombocytopenia and fever with palivizumab.
CONCLUSIONS: This post-marketing analysis suggests a comparable safety profile for both drugs. While very few adverse events were aligned with FDA labeling based on clinical trial data, additional safety signals were identified, necessitating an ongoing pharmacovigilance study to inform clinical and regulatory decision-making.
METHODS: We extracted adverse event reports from the FAERS and WHO VigiAccess databases from 2023 to 2025 and conducted signal detection using the Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and Empirical Bayesian Geometric Mean (EBGM) methods.
RESULTS: FAERS analysis identified 74 signals for nirsevimab and 91 signals for palivizumab. WHO-VigiAccess included 1,279 reports for nirsevimab and 22,290 reports for palivizumab. At the System Organ Classes (SOCs) level, both databases showed a similar distribution, with the most frequently reported categories including infections and infestations; respiratory, thoracic, and mediastinal disorders; and general disorders and administration site conditions. In FAERS, the preferred terms (PTs) with the highest signal intensity for nirsevimab were vaccination error (n= 5; ROR = 42,159.79; EBGM = 3,495.36) and RSV bronchiolitis (n = 222; ROR = 24,041.95; EBGM = 3,173.56). For palivizumab, the strongest signals were Subglottic laryngitis (n = 4; ROR = 1,230.46; EBGM = 682.96) and Bronchiolitis (n = 170; ROR = 524.84; EBGM = 371.59). Only a few events in either database align with FDA-approved labeling, such as rash with nirsevimab and severe thrombocytopenia and fever with palivizumab.
CONCLUSIONS: This post-marketing analysis suggests a comparable safety profile for both drugs. While very few adverse events were aligned with FDA labeling based on clinical trial data, additional safety signals were identified, necessitating an ongoing pharmacovigilance study to inform clinical and regulatory decision-making.
Conference/Value in Health Info
2026-05, ISPOR 2026, Philadelphia, PA, USA
Value in Health, Volume 29, Issue S6
Code
EPH74
Topic
Epidemiology & Public Health
Topic Subcategory
Safety & Pharmacoepidemiology
Disease
SDC: Pediatrics, SDC: Respiratory-Related Disorders (Allergy, Asthma, Smoking, Other Respiratory)