Overview
- UKHSA’s analysis, presented Saturday at ESCMID Global 2026, estimated 81.3% effectiveness when the vaccine was given at least 14 days before delivery.
- Protection rose to nearly 85% when mothers were vaccinated at least four weeks before giving birth.
- Babies born 10 to 13 days after maternal vaccination had about half as many RSV hospitalizations, while shots given less than 10 days before birth showed no measurable effect.
- Preterm infants also benefited when there was at least a two‑week interval between vaccination and birth, with effectiveness estimated at about 69.4%.
- The study followed 289,399 infants born in England from September 2024 to March 2025 and recorded 4,594 RSV-related admissions, with babies of unvaccinated mothers accounting for 87.2% of hospitalizations.