Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants

Background: Respiratory syncytial virus (RSV) is a leading cause of infant mortality globally. This phase 3 trial evaluated the efficacy of a bivalent RSV prefusion F protein based (RSVpreF) vaccine administered during pregnancy to prevent RSV associated lower respiratory tract illness (LRTI) in infants.

Methods: In a double blind, placebo controlled study across 18 countries, 7,358 pregnant women (24–36 weeks’ gestation) received RSVpreF vaccine (3,682) or placebo (3,676). Primary endpoints were medically attended severe RSV-associated LRTI and RSV-associated LRTI in infants within 180 days post birth.

Results: Vaccine efficacy was 81.8% (99.5% CI: 40.6–96.3) against severe RSV-LRTI within 90 days and 69.4% (97.58% CI: 44.3–84.1) within 180 days. No safety concerns were identified.

Conclusion: Maternal RSVpreF vaccination significantly reduced severe RSV LRTI in infants, supporting its use for neonatal protection.

Background: Respiratory syncytial virus (RSV) is a leading cause of infant mortality globally. This phase 3 trial evaluated the efficacy of a bivalent RSV prefusion F protein based (RSVpreF) vaccine administered during pregnancy to prevent RSV associated lower respiratory tract illness (LRTI) in infants.

Methods: In a double blind, placebo controlled study across 18 countries, 7,358 pregnant women (24–36 weeks’ gestation) received RSVpreF vaccine (3,682) or placebo (3,676). Primary endpoints were medically attended severe RSV-associated LRTI and RSV-associated LRTI in infants within 180 days post birth.

Results: Vaccine efficacy was 81.8% (99.5% CI: 40.6–96.3) against severe RSV-LRTI within 90 days and 69.4% (97.58% CI: 44.3–84.1) within 180 days. No safety concerns were identified.

Conclusion: Maternal RSVpreF vaccination significantly reduced severe RSV LRTI in infants, supporting its use for neonatal protection.