TOPLINE: 

Maternal respiratory syncytial virus prefusion F (RSVpreF) vaccination was associated with a substantial reduction in the risk for hospital admissions for RSV-related lower respiratory tract infections (LRTIs) in infants aged 90 days or younger, including those born preterm.

METHODOLOGY:

• Researchers in Scotland conducted a population-based, case-control study using linked datasets to estimate the effectiveness of maternal RSVpreF vaccination in preventing RSV-related LRTI hospitalisations among infants born between August 12, 2024, and March 31, 2025.
• Infants aged 90 days or younger with an admission for an RSV-related LRTI were included, with RSV confirmed by a positive polymerase chain reaction test within 14 days before or 2 days after admission.
• At the time of admission, 354 infants with an RSV-related LRTI (56.8% boys) were matched with 3511 control infants (52.2% boys) by week of birth and gestational age; control infants had not experienced any prior RSV event at the time of matching.
• Infants were classified as vaccinated if the maternal RSV vaccine was administered more than 14 days before delivery, suboptimally immunized if the maternal RSV vaccine was given 0-14 days before delivery, and unvaccinated if no dose was received during pregnancy.
• The study outcome was RSV-related LRTI hospitalisation in the first 90 days of life.

TAKEAWAY:

• Infants of mothers vaccinated more than 14 days before delivery had an 82.2% lower adjusted risk for RSV-related LRTI hospitalisations than infants of unvaccinated mothers (P < .0001), translating to an estimated 219 admissions averted during the study period.
• The adjusted vaccine effectiveness for preventing RSV-related LRTI hospitalisations remained high across gestational ages, at 89.9% (P = .0025) for preterm infants and 81.5% (P < .0001) for term infants.
• Suboptimal immunization offered no clear protection compared with no vaccination (adjusted vaccine effectiveness for suboptimal immunization, 31.7%; P = .20).
• Results were consistent in a cohort analysis that matched vaccinated and unvaccinated pregnant women by maternal age and gestational week at the date of vaccination.

IN PRACTICE:

"Our results suggest that the vaccination programme in Scotland has the potential to avert hundreds of further RSV-related LRTI hospital admissions in infants annually if coverage can be improved," the authors wrote.

"Continued efforts to raise awareness, address barriers to access, and support RSVpreF vaccination in routine antenatal care are vital to maximising the full public health impact of this immunisation programme not only in Scotland, but globally," they added.

SOURCE:

The study was led by Isobel McLachlan, PhD, Public Health Scotland in Glasgow, Scotland. It was published online on November 28, 2025, in The Lancet Infectious Diseases.

LIMITATIONS:

The study covered only one RSV season; therefore, it did not assess how long protection lasted or whether results changed across seasons. The number of preterm babies was insufficient to compare very preterm with moderately preterm infants. Additionally, the study did not account for breastfeeding, maternal health habits, or access to care, which could have affected vaccine uptake, RSV risk, and healthcare-seeking behaviour.

DISCLOSURES:

The study did not receive any funding. Some authors disclosed receiving research grants or institutional support, serving as consultants, or receiving personal honoraria from organizations such as the UK Medical Research Council, Public Health Scotland, the Gates Foundation, Pfizer, and others.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.