- Design
- Systematic review and meta-analysis of non-randomised post-implementation studies
- Population
- 7 studies, 7,112 infants in Argentina, the UK and the US
- Primary outcome
- RSV lower respiratory tract infection hospital admission
- Effect
- VE 82% (81 to 82) to 3 months; 78% (70 to 84) to 6 months
A systematic review and meta-analysis in JAMA Pediatrics (September 2026) pooled seven non-randomised post-implementation studies from Argentina, the UK and the US, covering 7,112 infants, 2,684 of them born to mothers given the bivalent RSV prefusion F vaccine (RSVpreF) in pregnancy. Data were collected from 2024 to 2025.
When mothers were vaccinated at least 14 days before delivery, effectiveness against RSV lower respiratory tract infection admission was 82% (95% CI 81% to 82%; three studies, I² 0%) up to three months of age and 78% (70% to 84%; six studies, I² 18.7%) up to six months. Data were too limited to pool emergency visits, intensive care admissions or deaths.
These are observational studies, open to confounding by who chose vaccination, and all came from settings with established programmes. But they agree closely with the pivotal trial, and heterogeneity was low.
The practical point for the paediatrician is timing: protection depended on vaccination at least two weeks before birth, and a baby born sooner after maternal vaccination may need a different plan.
- Ask at the first newborn check whether the mother received RSV vaccine in pregnancy, and when
- Treat a baby born less than 14 days after maternal vaccination as not reliably protected
- Support antenatal RSV vaccination where it is offered in your setting
- Keep counselling about RSV warning signs — protection is high but not complete
- Record maternal RSV vaccination in the infant's health record
Why it matters
It confirms outside a trial that a single antenatal dose protects most infants through the highest-risk months.
Don't overread it
These are observational studies from three high- and middle-income countries; confounding by who chose vaccination cannot be excluded.
The statistics, in plain English
Vaccine effectiveness of 82% means infants of vaccinated mothers had about one-fifth the odds of RSV admission of other infants. I² of 0% means the studies agreed, which strengthens confidence in the pooled figure.
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