What precautions should be taken to prevent Respiratory Syncytial Virus (RSV) infection in pregnancy?

Preventing RSV Infection in Pregnancy

The most effective way to prevent Respiratory Syncytial Virus (RSV) infection during pregnancy is through maternal RSV vaccination (RSVpreF) during 32-36 weeks' gestation, administered seasonally from September to January in most of the continental United States.1

Vaccination Recommendations

• The Centers for Disease Control and Prevention (CDC) recommends RSV vaccination for pregnant persons at 32-36 weeks' gestation during September-January in most of the continental United States 1
• Vaccination should be timed 1-2 months before the anticipated start of RSV season and continue through 2-3 months before the anticipated end of the season 1
• In regions with different RSV seasonality (Alaska, southern Florida, Guam, Hawaii, Puerto Rico, U.S.-affiliated Pacific Islands, and U.S. 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

Effectiveness and Safety

• Maternal RSV vaccination provides protection to infants during their most vulnerable period, though protection likely wanes after approximately 3 months 1, 2
• At least 14 days are needed after maternal vaccination for development and transplacental transfer of maternal antibodies to protect the infant 1, 2
• No statistically significant differences were observed between vaccine and placebo groups for preterm birth, low birthweight, or neonatal jaundice outcomes 1
• Current recommendations are for a single lifetime dose; no data are available on efficacy or safety of additional doses during subsequent pregnancies 1

Alternative Protection: Nirsevimab for Infants

• For infants whose mothers did not receive RSV vaccine during pregnancy, nirsevimab (a long-acting monoclonal antibody) is recommended for infants aged <8 months who are born during or entering their first RSV season 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, 2
• Recent data shows that 55.8% of infants were protected by maternal RSV vaccine, nirsevimab, or both during the 2023-24 RSV season 3

Additional Preventive Measures

• Keep high-risk infants away from crowds and situations where exposure to infected people cannot be controlled 1, 4
• Restrict participation in group child care during RSV season when feasible 1, 4
• Practice careful hand hygiene 1, 4
• Ensure all eligible infants and their contacts receive influenza vaccine and other age-appropriate immunizations 1, 4
• Eliminate exposure to tobacco smoke 4, 5

Risk Factors for Severe RSV Disease

• Gestational age ≤32 weeks 6, 5
• Prolonged perinatal oxygen requirement (≥28 days) 6
• NICU discharge within 3 months of the RSV season 6
• Male sex, household crowding, and daycare attendance 5
• Abbreviated breastfeeding (less than 2 months) 5

Common Pitfalls and Considerations

• Provider recommendation is strongly associated with higher immunization coverage; lack of recommendation is the main reason for not getting RSV immunization 3
• Concern about long-term safety for the infant is the main reason some parents decline nirsevimab 3
• RSV can cause significant illness in pregnant women themselves, with 50% of PCR-confirmed cases reporting lower respiratory tract symptoms 7
• Studies show pregnant women generally prefer maternal immunization over infant immunization for RSV protection 8