Objective To mine and analyze the adverse drug events (ADE) signals of nirsevimab based on the data from the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS).

Method Data were extracted from the FAERS for the period from January 1, 2023, to September 30, 2025. ADE signals were detected using 4 algorithms: the reporting odds ratio, proportional reporting ratio, Bayesian confidence propagation neural network, and multi-item gamma Poisson shrinker. Subgroup analysis, Weibull distribution analysis, and sensitivity analysis were also performed.

Results A total of 946 ADE reports were included, and 61 preferred terms were identified as positive signals. The system organ class with the highest reporting frequency and strongest signal intensity was infections and infestations, followed by respiratory, thoracic and mediastinal disorders. Known ADEs included pyrexia, rash, and injection site reaction. Unexpected signals were also detected, including cough, urticaria, oxygen therapy, wheezing, respiratory distress, poor feeding in infants, rhinitis and apnoea—some of which may indicate hypersensitivity reactions induced by nirsevimab. Stratified analysis revealed that neonates were at a higher risk of apnea. The median time to onset of ADEs was 23 days. Weibull analysis indicated an early peak of ADE risk. Sensitivity analysis confirmed the consistency and robustness of the data.

Conclusion Several newly identified potential risk signals not listed in the nirsevimab package insert were reported in this study, particularly those unexpected events related to hypersensitivity reactions. Further clinical studies are required to elucidate the underlying mechanisms and verify the causal relationship between nirsevimab and these ADEs.

1. LiY, WangX, BlauDM, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in children younger than 5 years in 2019: a systematic analysis[J]. Lancet, 2022, 399(10340): 2047-2064. DOI: 10.1016/S0140-6736(22)00478-0.

2. GuoL, DengS, SunS, et al. Respiratory syncytial virus seasonality, transmission zones, and implications for seasonal prevention strategy in China: a systematic analysis[J]. Lancet Glob Health, 2024, 12(6): e1005-e1016. DOI: 10.1016/S2214-109X(24)00090-1.

3. PollardKJ, Traina-DorgeV, MedearisSM, et al. Respiratory syncytial virus infects peripheral and spinal nerves and induces chemokine-mediated neuropathy[J]. J Infect Dis. 2024, 230(2): 467-479. DOI: 10.1093/infdis/jiad596.

4. ZhangS, AkmarLZ, BaileyF, et al. Cost of respiratory syncytial virus-associated acute lower respiratory infection management in young children at the regional and global level: a systematic review and Meta-analysis[J]. J Infect Dis, 2020, 222(S7): S680-S687. DOI: 10.1093/infdis/jiz683.

5. KeamSJ. Nirsevimab: first approval[J]. Drugs, 2023, 83(2): 181-187. DOI: 10.1007/s40265-022-01829-6.

6. GriffinMP, YuanY, TakasT, et al. Single-dose nirsevimab for prevention of RSV in preterm infants[J]. N Engl J Med, 2020, 383(5): 415-425. DOI: 10.1056/NEJMoa1913556.

7. DrysdaleSB, CathieK, FlameinF, et al. Nirsevimab for prevention of hospitalizations due to RSV in infants[J]. N Engl J Med, 2023, 389(26): 2425-2435. DOI: 10.1056/NEJMoa2309189.

8. HammittLL, DaganR, YuanY, et al. Nirsevimab for prevention of RSV in healthy late-preterm and term infants[J]. N Engl J Med, 2022, 386(9): 837-846. DOI: 10.1056/NEJMoa 2110275.

9. SimõesEAF, MadhiSA, MullerWJ, et al. Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: a pooled analysis of randomised controlled trials[J]. Lancet Child Adolesc Health, 2023, 7(3): 180-189. DOI: 10.1016/S2352-4642(22)00321-2.

10. SumsuzzmanDM, WangZ, LangleyJM, et al. Real-world effectiveness of nirsevimab against respiratory syncytial virus disease in infants: a systematic review and Meta-analysis[J]. Lancet Child Adolesc Health, 2025, 9(6): 393-403. DOI: 10.1016/S2352-4642(25)00093-8.

11. MankadVS, LeachA, ChangY, et al. Comprehensive summary of safety data on nirsevimab in infants and children from all pivotal randomized clinical trials[J]. Pathogens, 2024, 13(6): 503. DOI: 10.3390/pathogens13060503.

12. ShuY, HeX, LiuY, et al. A real-world disproportionality analysis of olaparib: data mining of the public version of FDA Adverse Event Reporting System[J]. Clin Epidemiol, 2022, 14: 789-802. DOI: 10.2147/CLEP.S365513.

13. HuY, BaiZ, TangY, et al. Fournier gangrene associated with sodium-glucose cotransporter-2 inhibitors: a pharmacovigilance study with data from the U.S. FDA Adverse Event Reporting System[J]. J Diabetes Res, 2020,2020: 1-8. DOI: 10.1155/2020/3695101.

14. LiuW, LinS, ZhuX, et al. Safety assessment of anti-B cell maturation antigen chimeric antigen receptor T cell therapy: a real-world study based on the FDA Adverse Event Reporting System Database[J]. Front Immunol, 2024, 15: 1433075. DOI: 10.3389/fimmu.2024.1433075.

15. XueF, PuL , LanS, et al. Adverse drug reaction signal detection methods in spontaneous reporting system: a systematic review[J]. Pharmacoepidemiol Drug Saf, 2024, 33(3): e5768. DOI: 10.1002/pds.5768.

16. 胡晔, 龚奇能, 张琳琳, 等. 基于FAERS数据库的氘可来昔替尼不良事件信号挖掘与分析[J]. 药物流行病学杂志, 2025, 34(4): 419-427.HuY, GongQN, ZhangLL, et al. Signals mining and analysis of deucravacitinib adverse drug events based on FAERS database[J]. Chinese Journal of Pharmacoepidemiology, 2025, 34(4): 419-427. DOI: 10.12173/j.issn.1005-0698. 202412084.

17. DomachowskeJ, MadhiSA, SimõesEAF, et al. Safety of nirsevimab for rsv in infants with heart or lung disease or prematurity[J]. N Engl J Med, 2022, 386(9): 892-894. DOI: 10.1056/NEJMc2112186.

18. Estrella-PorterP, Correcher-MartínezE, Orrico-SánchezA, et al. Post-marketing surveillance of nirsevimab: safety profile and adverse event analysis from Spain's 2023-2024 RSV immunisation campaign[J]. Vaccines (Basel), 2025, 13(6): 623. DOI: 10.3390/vaccines 13060623.

19. ConsolatiA, FarinelliM, SerravalleP, et al. Safety and efficacy of nirsevimab in a universal prevention program of respiratory syncytial virus bronchiolitis in newborns and infants in the first year of life in the Valle d'Aosta Region, Italy, in the 2023–2024 Epidemic Season[J]. Vaccines (Basel), 2024, 12(5): 549. DOI: 10.3390/vaccines12050549.

20. HanselTT, KropshoferH, SingerT, et al. The safety and side effects of monoclonal antibodies[J]. Nat Rev Drug Discov, 2010, 9(4): 325-338. DOI: 10.1038/nrd3003.

21. WegzynC, TohLK, NotarioG, et al. Safety and effectiveness of palivizumab in children at high risk of serious disease due to respiratory syncytial virus infection: a systematic review[J]. Infect Dis Ther, 2014, 3(2): 133-158. DOI: 10.1007/s40121-014-0046-6.

22. 杜博冉, 封学伟, 冯欣, 等. 基于失效模式与效应分析的尼塞韦单抗临床应用患者管理和潜在风险防范专家共识[J]. 中国医院用药评价与分析, 2025, 25(10): 1153-1156,1162.DuBR, FengXW, FengX, et al. Expert consensus on patient management and potential risk prevention in clinical application of nirsevimab based on failure mode and effect analysis[J]. Evaluation and Analysis of Drug-Use in Hospital of China, 2025, 25(10): 1153-1156,1162. DOI: 10.14009/j.issn.1672-2124.2025.10.001.

23. CarcioneD, SpencerP, PettigrewG, et al. Active post-marketing safety surveillance of nirsevimab administered to children in Western Australia, April–July 2024[J]. Pediatr Infect Dis J, 2025, 44(5): e174-e176. DOI: 10.1097/INF.0000000000004715.

24. KearnsGL, Abdel-RahmanSM, AlanderSW, et al. Developmental pharmacology-drug disposition, action, and therapy in infants and children[J]. N Engl J Med, 2003, 349(12): 1157-1167. DOI: 10.1056/NEJMra035092.