Maternal RSVpreF 78% effective against infant RSV hospitalization

Vaccinating pregnant patients with the respiratory syncytial virus (RSV) bivalent prefusion F protein vaccine (RSVpreF; Abrysvo) at least 14 days before delivery was 78% effective against RSV-associated lower respiratory tract infection (LRTI) hospitalization in infants from birth to 6 months, according to a systematic review and meta-analysis of real-world data published in JAMA Pediatrics.¹

The analysis pooled 7 postimplementation studies from Argentina, the UK, and the US and found real-world protection at least as high as that reported in the pivotal clinical trial.¹ Investigators led by Bahaa Abu-Raya, MD, PhD, of the Canadian Center for Vaccinology at Dalhousie University in Halifax, Nova Scotia, concluded that the results support adding RSVpreF to routine antenatal immunization programs, writing that integrating the vaccine into antenatal care "offers a scalable opportunity to address disparities in respiratory protection" among vulnerable newborns.¹

Real-world RSVpreF effectiveness against infant RSV hospitalization

The researchers searched PubMed, Scopus, and Europe PMC through January 30, 2026, and included 7 observational case-control studies, most using a test-negative design.¹ Together, the studies comprised 7112 infants, 2684 of whom were born to vaccinated mothers, with data collected from January 2024 through April 2025.¹ Vaccine effectiveness (VE) was calculated as (1 − odds ratio) × 100% using random-effects models.¹

When mothers were vaccinated 14 days or more before delivery, pooled VE against RSV-associated LRTI hospitalization was 82% (95% CI, 81%-82%; 3 studies; 4397 participants; I² = 0%) in infants from birth to 3 months and 78% (95% CI, 70%-84%; 6 studies; 3008 participants; I² = 18.7%) in infants from birth to 6 months.¹ Among studies that also counted vaccination at any time in pregnancy, VE from birth to 6 months was 68% (95% CI, 53%-78%; 3 studies; 984 participants).¹ Neither the decline with infant age nor the difference by vaccination timing was statistically significant.¹

How real-world RSVpreF data compare with the MATISSE trial

In the phase 3 MATISSE trial, RSVpreF prevented approximately 82% and 70% of medically attended severe RSV-associated LRTI within 90 and 180 days after birth, respectively.² Trial efficacy against RSV-associated LRTI hospitalization was 69.7% (95% CI, 37.1%-86.7%) and 55.3% (95% CI, 23.8%-74.6%) at the same time points.¹

The authors cautioned that overlapping CIs preclude a definitive conclusion that real-world performance is superior.¹ They noted that MATISSE administered the vaccine at 24 to 36 weeks' gestation, whereas mothers in the included studies were most commonly vaccinated at 32 to 36 weeks; in the trial, vaccination at 24 to 28 weeks was associated with lower efficacy and immune responses.¹ Differences in populations, testing strategies, and settings may also contribute.¹

Maternal RSV vaccine timing and US recommendations

In the US, the Centers for Disease Control and Prevention recommends a single dose of RSVpreF during 32 through 36 weeks' gestation using seasonal administration to protect infants after birth.³ National recommendations generally consider infants protected when maternal vaccination occurs at least 14 days before delivery.¹

Although maternally derived RSV F-specific IgG has an estimated half-life of approximately 38 days in infants, the authors found that effectiveness against hospitalization appeared to be maintained through 6 months of life.¹ They also pointed to a prior meta-analysis reporting 83% real-world effectiveness for nirsevimab against RSV-related hospitalization.¹

Limitations of the RSVpreF effectiveness meta-analysis

All but 1 study captured the first RSV season after program launch, so relatively few infants older than 3 months were likely represented, and the 0- to 6-month estimate may largely reflect younger infants.¹ Overall risk of bias was rated moderate to serious, with 3 retrospective studies judged at serious risk of confounding.¹ Four Argentine studies covered overlapping periods in 2024, although maximum potential participant overlap was estimated at 2.7%.¹

Data were insufficient to analyze emergency department visits, intensive care unit admissions, or death, and none of the studies reported mortality.¹ Effectiveness in preterm infants could not be assessed.¹ The authors called for further research in infants at higher risk of severe disease, against more severe outcomes, and with vaccination in the late second trimester.¹

References

1. Batool R, Wang R, Obeid H, et al. RSV bivalent prefusion F protein vaccine in pregnancy and protection against RSV-associated illness in infants: a systematic review and meta-analysis. JAMA Pediatr. 2026;180(11):1213-1221. doi:10.1001/jamapediatrics.2026.4074

2. Kampmann B, Madhi SA, Munjal I, et al; MATISSE Study Group. Bivalent prefusion F vaccine in pregnancy to prevent RSV illness in infants. N Engl J Med. 2023;388(16):1451-1464. doi:10.1056/NEJMoa2216480

3. Centers for Disease Control and Prevention. CDC recommends new vaccine to help protect babies against severe respiratory syncytial virus (RSV) illness after birth. Press release. September 22, 2023. Accessed November 5, 2026. https://www.cdc.gov/media/releases/2023/p0922-RSV-maternal-vaccine.html