Is the RSV (Respiratory Syncytial Virus) vaccine indicated in pregnancy?

RSV Vaccination in Pregnancy

The RSV vaccine (RSVpreF) is recommended for pregnant persons as a one-time dose at 32 weeks 0 days to 36 weeks 6 days gestation during seasonal administration periods (September-January in most of the continental United States) to prevent RSV-associated lower respiratory tract illness in infants aged <6 months. 1

Timing and Administration Guidelines

• RSV maternal vaccination should be administered during the window of 32-36 weeks gestation to optimize protection for infants during their most vulnerable period 1
• Seasonal administration (September-January in most of continental US) targets pregnant persons whose infants will be in their first months of life during RSV season 1
• In regions with different RSV seasonality patterns (Alaska, southern Florida, Guam, Hawaii, Puerto Rico, US-affiliated Pacific Islands, US Virgin Islands), providers should follow local guidance on vaccination timing 1
• RSV vaccine can be administered simultaneously with other recommended vaccines for pregnant persons (Tdap, influenza, COVID-19) at different anatomic sites on the same day 1

Efficacy and Protection

• Maternal RSVpreF vaccination was effective against medically attended severe RSV-associated lower respiratory tract illness in infants, with vaccine efficacy of 81.8% within 90 days after birth 2
• Protection from maternal vaccination likely wanes after approximately 3 months, similar to patterns observed with maternal influenza and COVID-19 vaccines 1
• At least 14 days are needed after maternal vaccination for development and transplacental transfer of maternal antibodies to protect the infant 1

Safety Considerations

• No significant safety signals were detected in maternal participants or in infants up to 24 months of age in the Pfizer RSVpreF vaccine trial 2
• The incidence of adverse events was similar between vaccine and placebo groups (13.8% vs 13.1% in women; 37.1% vs 34.5% in infants) 2
• Local injection site reactions are common but generally mild to moderate 3
• No statistically significant differences were observed between vaccine and placebo groups for preterm birth, low birthweight, or neonatal jaundice outcomes 1

Important Caveats and Considerations

• Current recommendations are for a single lifetime dose; no data are available on efficacy or safety of additional doses during subsequent pregnancies 1
• Nirsevimab (RSV antibody) is recommended for infants born to mothers who did not receive the RSV vaccine, whose mother's vaccination status is unknown, or who were born <14 days after maternal vaccination 1
• Either maternal RSV vaccination or infant nirsevimab administration is recommended, but both are not needed for most infants 1
• Nirsevimab is recommended for all infants born at <34 weeks gestation, regardless of maternal vaccination status 1
• Provider recommendation significantly impacts vaccination rates - only 32.6% of eligible pregnant women reported receiving the RSV vaccine during the 2023-24 RSV season 4

Decision-Making Algorithm

1. Confirm gestational age is between 32 weeks 0 days and 36 weeks 6 days 1
2. Verify current month is within seasonal administration period (September-January in most of US) 1
3. Assess for any contraindications to vaccination
4. Discuss relative advantages of maternal vaccination versus infant nirsevimab with the patient 1
5. If proceeding with vaccination, can administer simultaneously with other recommended vaccines 1
6. Document administration and expected delivery date to determine if infant will need nirsevimab based on timing of birth relative to vaccination 1