Maternal RSV Vaccination Reduces RSV Hospitalizations in Young Infants: JAMA

To conduct a proper evaluation of the actual protective effect provided by the maternal vaccination strategy, researchers designed a carefully controlled case-control study in one healthcare organization located in western Pennsylvania. The clinical chart review included the information collected from two sequential post-approval RSV seasons, both 2023–2024 and 2024–2025 cycles. Study participants were infants no older than 90 days old born within certain seasonal blocks, particularly between October 1, 2023, and April 15, 2024, or between September 1, 2024, and April 30, 2025, and admitted to hospitals for the treatment of ARIs.

In order to select cases and controls, test-negative design was used, meaning that infants were regarded as cases if they had received positive results of RSV molecular nucleic acid amplification and/or rapid antigen tests; otherwise, infants were considered controls. The strict eligibility criteria for maternal exposure to RSVpreF vaccine included vaccination between 32 weeks 0 days and 36 weeks 6 days gestation at least two weeks before delivery. Logistic regression was performed to calculate adjusted odds ratios for estimating vaccine effectiveness.

Key findings:

• The multi-season test-negative design yielded successful evaluation of a total sample of 274 infants admitted to the hospital, including 83 RSV-positive infants and 191 RSV-negative infants.
• The analyzed infants' age upon admission to the hospital was 29.5 ± 21.1 days, while the gender distribution of the studied infants was balanced with 143 male infants (52.2%).
• Among the studied samples, 13.3% of RSV-positive infants (11 out of 83 infants) were born of women who had received the vaccine, while 37.2% of the healthy infants (71 out of 191 infants) had been vaccinated as fetuses.
• The estimated vaccine effectiveness calculated using the adjusted regression models resulted in exactly 67.6% (95% CI, 33.2%–85.4%) against RSV-associated ARI hospitalizations between 0 and 90 days of life.
• In addition, the maternal vaccine showed secondary effectiveness rate against severe RSV-associated LRTD hospitalizations from birth up to 90 days of age with 69.0% (95% CI, 25.5%–88.0%) of protection.
• The highest vaccine effectiveness of 74.2% (95% CI, 25.4%–93.0%) was observed against RSV-associated ARI hospitalizations among very vulnerable infants aged from 0 to 30 days.

In summary, RSVpreF maternal vaccination was linked to the prevention of RSV-related ARI and LRTD hospitalizations among infants 90 days old or less. In sum, the results obtained here represent preliminary clinical proof of the efficacy of RSVpreF maternal vaccinations to prevent hospitalization related to RSV infections in infants. As such, this post-licensure research constitutes crucial empirical evidence in modern preventative pediatric care, illustrating how preemptive maternal healthcare translates to significant infant disease reduction.

Reference:

Rick A, Deese J, Kerr JE, et al. Maternal Respiratory Syncytial Virus Prefusion F Vaccination and Acute Respiratory Illness in Infants. JAMA Netw Open. 2026;9(6):e2616773. doi:10.1001/jamanetworkopen.2026.16773