Maternal Vaccination vs Nirsevimab Use and Respiratory Syncytial Virus Infection Among Full-Term Infants
- 1Vaccine Study Center, Kaiser Permanente Northern California Division of Research, Oakland, California
Abstract
Importance: Since 2023, infants can be protected from respiratory syncytial virus (RSV) through a vaccine (RSVpreF) for pregnant persons or a monoclonal antibody (nirsevimab) for infants.
Objective: To assess the relative product effectiveness (rPE) of maternal RSVpreF vs infant nirsevimab against RSV infection and hospitalization among infants born in the 2023 to 2025 RSV seasons.
Design, Setting, and Participants: This retrospective cohort study included full-term infants born at Kaiser Permanente Northern California (KPNC), an integrated health care system with approximately 40 000 births each year, from December 3, 2023, to March 30, 2024, or September 29, 2024, to March 15, 2025. Infants protected by RSVpreF were matched to infants protected with nirsevimab with optimal full matching (up to 1:5), adjusting for birth week, sex, and maternal factors. Each group was also compared with infants with no protection, matching unprotected infants to both RSVpreF and nirsevimab infants (up to 1:10).
Exposures: Maternal RSVpreF at 32 to 36 weeks’ gestation or infant nirsevimab through age 7 days.
Main Outcomes and Measures: Polymerase chain reaction (PCR)–confirmed RSV and RSV hospitalization (PCR-confirmed RSV 10 days before to 7 days after hospitalization) in infants aged 8 to 180 days or through RSV season end (April 30 in both seasons). rPE was estimated from age 8 to 180 days using restricted mean time lost.
Results: Of 15 124 matched infants (7729 [51.1%] male) in the primary analysis, 146 (0.97%) had RSV infection (106 of 11 293 [0.94%] in RSVpreF group and 40 of 3831 [1.04%] in nirsevimab group) and 12 (0.08%) were hospitalized (7 [0.06%] in RSVpreF group and 5 [0.13%] in nirsevimab group). The rPE of RSVpreF vs nirsevimab was −5.3% (95% CI, −44.8% to 23.4%) against infection and 61.5% (95% CI, −10.8% to 86.7%) against hospitalization. Compared with no protection, RSVpreF rPE was 69.3% (95% CI, 59.9% to 76.6%) against infection and 86.4% (95% CI, 66.4% to 94.5%) against hospitalization; nirsevimab rPE was 65.2% (95% CI, 51.0%-75.4%) and 73.8% (95% CI, 33.4%-89.7%), respectively.
Conclusion: In this cohort study of infants born in the 2023 to 2024 and 2024 to 2025 RSV seasons, no statistically significant difference between maternal RSVpreF and infant nirsevimab in RSV infection or hospitalization was detected. Compared with no protection, both products were associated with fewer infections and hospitalizations. This study supports current US guidelines for either maternal RSVpreF or infant nirsevimab to protect all infants from RSV.
Related
- Uptake of Respiratory Syncytial Virus Prefusion F Protein Vaccination during Pregnancy and nirsevimab among Infants over Two Seasons in a Single Health System.
- Respiratory syncytial virus vaccination during pregnancy confers higher anti-RSV IgG concentration in neonatal cord than maternal blood
- Assessing the Effects of Nirsevimab on Respiratory Syncytial Virus Bronchiolitis Outcomes: Insights From A Two‐Season Analysis
- Age-related clinical characteristics of respiratory syncytial virus infection in hospitalized children: a retrospective study
- Real-world emergence of nirsevimab resistance in breakthrough infections with respiratory syncytial virus-B: a multicentre observational study in France
BibTeX
@article{jacobson2026maternal,
title = {{Maternal Vaccination vs Nirsevimab Use and Respiratory Syncytial Virus Infection Among Full-Term Infants}},
author = {Karen B. Jacobson and Andrew J. Watson and Lauren D. Liao and Sally C. Stephens and Maqdooda Merchant and Ousseny Zerbo and Nicola P. Klein},
journal = {JAMA Network Open},
year = {2026},
month = oct,
doi = {10.1001/jamanetworkopen.2026.36760},
url = {https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2855505},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Maternal Vaccination vs Nirsevimab Use and Respiratory Syncytial Virus Infection Among Full-Term Infants
AU - Karen B. Jacobson
AU - Andrew J. Watson
AU - Lauren D. Liao
AU - Sally C. Stephens
AU - Maqdooda Merchant
AU - Ousseny Zerbo
AU - Nicola P. Klein
PY - 2026
DA - 2026/10/01
JO - JAMA Network Open
DO - 10.1001/jamanetworkopen.2026.36760
UR - https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2855505
AB - Importance: Since 2023, infants can be protected from respiratory syncytial virus (RSV) through a vaccine (RSVpreF) for pregnant persons or a monoclonal antibody (nirsevimab) for infants. Objective: To assess the relative product effectiveness (rPE) of maternal RSVpreF vs infant nirsevimab against RSV infection and hospitalization among infants born in the 2023 to 2025 RSV seasons. Design, Setting, and Participants: This retrospective cohort study included full-term infants born at Kaiser Permanente Northern California (KPNC), an integrated health care system with approximately 40 000 births each year, from December 3, 2023, to March 30, 2024, or September 29, 2024, to March 15, 2025. Infants protected by RSVpreF were matched to infants protected with nirsevimab with optimal full matching (up to 1:5), adjusting for birth week, sex, and maternal factors. Each group was also compared with infants with no protection, matching unprotected infants to both RSVpreF and nirsevimab infants (up to 1:10). Exposures: Maternal RSVpreF at 32 to 36 weeks’ gestation or infant nirsevimab through age 7 days. Main Outcomes and Measures: Polymerase chain reaction (PCR)–confirmed RSV and RSV hospitalization (PCR-confirmed RSV 10 days before to 7 days after hospitalization) in infants aged 8 to 180 days or through RSV season end (April 30 in both seasons). rPE was estimated from age 8 to 180 days using restricted mean time lost. Results: Of 15 124 matched infants (7729 [51.1%] male) in the primary analysis, 146 (0.97%) had RSV infection (106 of 11 293 [0.94%] in RSVpreF group and 40 of 3831 [1.04%] in nirsevimab group) and 12 (0.08%) were hospitalized (7 [0.06%] in RSVpreF group and 5 [0.13%] in nirsevimab group). The rPE of RSVpreF vs nirsevimab was −5.3% (95% CI, −44.8% to 23.4%) against infection and 61.5% (95% CI, −10.8% to 86.7%) against hospitalization. Compared with no protection, RSVpreF rPE was 69.3% (95% CI, 59.9% to 76.6%) against infection and 86.4% (95% CI, 66.4% to 94.5%) against hospitalization; nirsevimab rPE was 65.2% (95% CI, 51.0%-75.4%) and 73.8% (95% CI, 33.4%-89.7%), respectively. Conclusion: In this cohort study of infants born in the 2023 to 2024 and 2024 to 2025 RSV seasons, no statistically significant difference between maternal RSVpreF and infant nirsevimab in RSV infection or hospitalization was detected. Compared with no protection, both products were associated with fewer infections and hospitalizations. This study supports current US guidelines for either maternal RSVpreF or infant nirsevimab to protect all infants from RSV.
SN - 2574-3805
ER -