Passive Infant Immunization With Nirsevimab Lowers RSV Hospitalization Risk Compared With Maternal RSVpreF Vaccination: JAMA
France: Researchers have found in a new study that passive infant immunization with nirsevimab was associated with lower risks of RSV-related hospitalization and severe disease compared with maternal RSVpreF vaccination during the first RSV season in mainland France, warranting further evaluation in future studies.
Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections and hospitalization in infants, especially in early life. With the rollout of maternal vaccination and passive infant immunization, their real-world comparative effectiveness remains uncertain.
Addressing this gap, researchers led by Marie-Joelle Jabagi from the French National Agency for Medicines and Health Products Safety and the French National Health Insurance (EPI-PHARE) conducted a nationwide population-based cohort study to compare these two approaches.
The study, published in JAMA, used data from the French National Health Data System and included infants born in mainland France between September 1 and December 31, 2024. Maternal vaccination with the RSV prefusion F protein (RSVpreF) vaccine was administered between 32 and 36 weeks of gestation, while passive infant immunization with nirsevimab was given before hospital discharge.
To ensure comparability, infants in the two groups were matched one-to-one based on discharge date from the maternity ward, sex, gestational age, and region of birth. Follow-up continued until RSV-related hospitalization, death, or the end of the RSV season on February 28, 2025.
The study led to the following notable findings:
- The analysis included 42,560 newborns, with 21,280 infants in each study group.
- The median follow-up duration was approximately three months.
- A total of 481 infants were hospitalized for RSV-associated lower respiratory tract infection during follow-up.
- RSV-related hospitalizations were fewer among infants who received nirsevimab than among those whose mothers received the RSVpreF vaccine.
- After adjustment for potential confounders, passive immunization with nirsevimab was associated with a significantly lower risk of RSV-related hospitalization.
- Nirsevimab was also linked to reduced risks of severe RSV disease.
- Infants in the nirsevimab group were less likely to require pediatric intensive care unit admission.
- The need for ventilator support and oxygen therapy was lower among infants who received nirsevimab compared with those protected through maternal vaccination.
The researchers noted that consistent results across subgroup and sensitivity analyses strengthen confidence in the findings, suggesting that passive infant immunization may provide stronger protection during the early months of life, when infants are most vulnerable to severe RSV infection.
However, the authors cautioned that the results reflect only the first RSV season in France in which both strategies were used simultaneously. They emphasized the need for longer-term follow-up and additional studies across multiple seasons and settings to better assess the durability of protection, cost-effectiveness, and broader population impact.
Overall, the authors concluded that this early real-world evidence indicates nirsevimab may offer greater protection against RSV-related hospitalization and severe disease in newborns than maternal RSVpreF vaccination, with potential implications for future immunization policy and clinical practice.
Reference:
Jabagi M, Bertrand M, Gabet A, Kolla E, Olié V, Zureik M. Nirsevimab vs RSVpreF Vaccine for Respiratory Syncytial Virus–Related Hospitalization in Newborns. JAMA. Published online December 22, 2025. doi:10.1001/jama.2025.24082
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