RSV Vaccine for Pregnant Women
The RSV vaccine approved for pregnant women is Abrysvo (RSVpreF vaccine, manufactured by Pfizer Inc.). 1
Vaccine Details
Abrysvo is a bivalent RSVpreF vaccine containing stabilized prefusion F glycoproteins from both RSV A and RSV B strains. It is administered as a single 0.5 mL intramuscular injection 1.
Recommended Timing
Administer at 32-36 weeks' gestation (specifically 32 weeks and 0 days through 36 weeks and 6 days) during September through January in most of the continental United States 1. This seasonal timing ensures infants receive maximum protection during their first months of life when RSV circulation peaks.
Geographic Variations
For Alaska, southern Florida, Guam, Hawaii, Puerto Rico, U.S.-affiliated Pacific Islands, and U.S. Virgin Islands, follow local guidance as RSV seasonality differs from the continental U.S. 1
Key Safety Considerations
The FDA approval came with important caveats based on clinical trial data:
Preterm birth signal: More preterm births (<37 weeks) were observed in vaccinated versus placebo groups, though differences were not statistically significant 1. The 32-36 week window was specifically chosen to avoid potential preterm birth risk at <32 weeks' gestation, which carries higher morbidity and mortality 1
Hypertensive disorders: Increased hypertensive disorders of pregnancy were noted in vaccine recipients versus placebo, though again not statistically significant 1. Recent meta-analysis data suggest a small but statistically significant increase in overall HDP risk (RR 1.08,95% CI 1.02-1.13), driven primarily by gestational hypertension rather than preeclampsia 2
FDA determination: Despite these signals, the FDA concluded that benefits of preventing RSV-associated lower respiratory tract infection in infants outweigh the potential risks when administered at 32-36 weeks 1
Alternative Option
Either maternal RSVpreF vaccination OR nirsevimab (Beyfortus) administration to the infant is recommended—but both are not needed for most infants 1. This provides flexibility based on patient circumstances and preferences.
When Nirsevimab is Preferred:
- Infants born <14 days after maternal vaccination (insufficient time for antibody transfer) 1
- Infants born outside RSV season (April-September) who will be <8 months at RSV season onset 1
- Patient preference to avoid potential pregnancy risks
Co-administration
Abrysvo can be given simultaneously with other recommended vaccines including Tdap, influenza, and COVID-19 vaccines at different anatomic sites 1.
Important Clinical Pitfall
One-time lifetime dose: Currently, there are no data on safety or efficacy of repeat doses in subsequent pregnancies. ACIP may update recommendations as data emerge 1.