Can a pregnant woman at 35 weeks gestation receive a respiratory syncytial virus (RSV) vaccine today?

Can a Pregnant Woman at 35 Weeks Gestation Receive RSV Vaccine Today?

Yes, a pregnant woman at 35 weeks gestation can receive the RSV vaccine today if it is currently September through January in most of the continental United States, as the CDC recommends maternal RSVpreF vaccination between 32 weeks 0 days and 36 weeks 6 days gestation during RSV season. 1

Gestational Age Window

• The approved dosing interval is 32 weeks 0 days through 36 weeks 6 days gestation, making 35 weeks well within the recommended window 1
• At 35 weeks, there is adequate time for antibody development and transplacental transfer, which requires at least 14 days after vaccination to protect the infant 2, 3

Seasonal Timing Requirements

• Maternal RSVpreF vaccination should only be administered during September through January in most of the continental United States 1
• If today's date falls outside this seasonal window, do not administer the vaccine—instead, plan for infant nirsevimab administration after delivery 2
• Different timing applies to Alaska, southern Florida, Guam, Hawaii, Puerto Rico, U.S.-affiliated Pacific Islands, and U.S. Virgin Islands, where providers should follow local guidance 1

Safety Considerations at This Gestational Age

• In the approved 32-36 week interval, preterm births occurred in 4.2% of vaccine recipients versus 3.7% of placebo recipients, a difference that was not statistically significant 4
• The FDA determined that benefits outweigh risks when administered at 32-36 weeks gestation, including the potential for preterm birth and hypertensive disorders of pregnancy 3, 4
• Most preterm births in the approved interval occurred at 36 weeks' gestation, accounting for 72% of vaccine group preterm births 4

Efficacy at This Timing

• The vaccine demonstrates 81.8% efficacy against medically attended severe RSV-associated lower respiratory tract illness within 90 days after birth 5
• When given at 32-36 weeks, efficacy is 76.5% against severe RSV-associated lower respiratory tract illness and 48.2% against RSV hospitalization 3
• Protection is immediate after birth due to transplacental antibody transfer, with antibodies expected to wane after approximately 3 months 2

Critical Implementation Points

• Administer as a single 0.5 mL intramuscular dose 3
• The vaccine can be co-administered with other pregnancy vaccines (Tdap, influenza, COVID-19) at different anatomic sites on the same day 1
• Do not plan to give infant nirsevimab if maternal vaccination is administered today, as both products are not needed for most infants 2, 3

Key Pitfalls to Avoid

• Do not administer the vaccine if the current date is outside September-January in most continental U.S. regions 1
• Do not give the vaccine if the patient has a history of severe allergic reaction (anaphylaxis) to any vaccine component 2
• Do not vaccinate if the patient has moderate or severe acute illness with or without fever; delay vaccination until recovery 2
• If delivery occurs less than 14 days after vaccination, the infant may not be adequately protected and should receive nirsevimab instead 2, 3