Maternal RSV vaccination vs. infant nirsevimab for prevention of RSV infection

Infants can be protected from respiratory syncytial virus (RSV) infection through a vaccine (RSVpreF, Abrysvo) given to pregnant persons or a monoclonal antibody (nirsevimab) administered to infants. A recent U.S. study assessed the relative product effectiveness of maternal vaccination compared with infant nirsevimab against RSV infection and hospitalization among infants born in the 2023–2024 and 2024–2025 RSV seasons.1The retrospective cohort study included data on full-term infants born at an integrated healthcare system in Northern California from December 3, 2023 to March 30, 2024, or September 29, 2024 to March 15, 2025. Infants protected by maternal RSVpreF vaccination 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).1Maternal RSVpreF vaccination was given at 32–36 weeks’ gestation, while infant nirsevimab was administered during the first seven days of the infant’s life.1The main outcome was polymerase chain reaction (PCR)–confirmed RSV and RSV hospitalization (PCR-confirmed RSV 10 days before to 7 days after hospitalization) in infants aged 8–180 days or through to the RSV season end (April 30 in both seasons). Relative product effectiveness was estimated from age 8–180 days.1Key results:Of 15,124 matched infants (51.1% male) in the primary analysis, 146 (0.97%) developed RSV infection—106 of 11, 293 (0.94%) in RSVpreF group and 40 of 3,831 (1.04%) in nirsevimab group).A total of 12 (0.08%) infants with RSV infection were hospitalized—7 (0.06%) in the RSVpreF group and 5 (0.13%) in nirsevimab group.The relative product effectiveness of RSVpreF versus 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 relative product effectiveness was 69.3% (95% CI, 59.9%–76.6%) against infection and 86.4% (95% CI, 66.4%–94.5%) against hospitalization, while nirsevimab relative product effectiveness was 65.2% (95% CI, 51.0%–75.4%) against infection and 73.8% (95% CI, 33.4%–89.7%) against hospitalization.1The authors concluded that in this cohort study of infants born in the 2023–2024 and 2024–2025 RSV seasons, no statistically significant difference was detected between maternal vaccination with RSVpreF and infant nirsevimab in the occurrence of RSV infection or RSV hospitalization.1 Compared with no protection, both products were associated with fewer infections and hospitalizations in infants 180 days or younger.1 ReferenceJacobson KB, Watson AJ, Liao LD, et al. Maternal vaccination vs nirsevimab use and respiratory syncytial virus infection among full-term infants. JAMA Netw Open 2026;9;(10):e2636760. Published Online: October 24, 2026 (accessed October 27, 2026)

Maternal RSV vaccination vs. infant nirsevimab for prevention of RSV infection

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