Peer-reviewed article
Safety of nirsevimab in children aged 0-24 months: Analysis based on EudraVigilance data (2023-2025).
Cristina Morciano, Arianna Annunziata, Maria Cutillo, Flavia Mayer, Stefania Spila Alegiani ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This study examined adverse reactions reported after nirsevimab, a preventive monoclonal antibody against respiratory syncytial virus (RSV), was given to infants aged 0-24 months across European Union countries between 2023 and 2025. The researchers analyzed 1,923 adverse reactions from 808 cases reported in the EudraVigilance safety monitoring system. Most reported reactions were general symptoms and injection site reactions, infections, or respiratory issues, with the most common being ineffective drug response and RSV bronchiolitis. The safety profile observed in routine practice matched findings from earlier clinical trials.
Key points
- 1,923 adverse drug reactions were reported across 808 cases following nirsevimab administration in children aged 0-24 months
- Most common adverse reactions were general disorders and administration site conditions (28.4%), infections and infestations (23.3%), and respiratory disorders (12.2%)
- The most frequently reported reactions were drug ineffective (12.6%) and RSV bronchiolitis (9.6%), followed by fever, rash, and injection site reactions
- Reported adverse reactions in routine practice were consistent with safety findings from pre-approval clinical trials
- The study supports continued monitoring of nirsevimab safety in real-world settings
Limitations
This analysis describes reported adverse reactions only and does not calculate rates of adverse events relative to the total number of doses administered, so the true frequency of reactions cannot be determined. The study is based on spontaneous reporting data, which may be subject to underreporting or reporting bias.
Abstract
Respiratory syncytial virus (RSV) is a cause of severe lower respiratory tract infections in infants, and it is associated with substantial morbidity, including hospitalization and death. After European Medicine Agency approval of nirsevimab, a monoclonal antibody against RSV, immunization campaigns have been implemented in several European Union countries for administration to children as preventive intervention against severe RSV disease during RSV epidemic season. Monitoring its safety in routine healthcare practice is also important. We described suspected adverse drug reactions (ADRs) following nirsevimab administration in children aged 0-24 months, reported in the EudraVigilance system between 2023 and 2025. There were 1,923 ADRs, corresponding to 808 cases. By System Organ Class, ADRs mainly included general disorders and administration site conditions, which include nonspecific systemic manifestations and administration-site reactions that cannot be readily assigned to a single organ system (28.4%), infections and infestations (23.3%), respiratory, thoracic, and mediastinal disorders (12.2%); by Preferred Terms most frequent were drug ineffective (12.6%), and RSV bronchiolitis (9.6%). In addition, pyrexia, rash, and injection site reactions were also common. This study offered systematic characterization of ADRs following administration of nirsevimab. It found that the reported ADRs are consistent with the safety results from pre- and real-world safety studies. Our study can support the continue monitoring of the real-world safety and guide the planning of analytical observational studies on the safety profile of nirsevimab.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Nirsevimab immunization (monoclonal antibody against RSV) administered to children aged 0-24 months during RSV epidemic season
- Population
- Children aged 0-24 months in European Union countries who received nirsevimab
Key finding
1,923 adverse drug reactions from 808 cases reported following nirsevimab administration
Morciano et al. · PubMed (US National Library of Medicine) · 9 Oct 2026