Prenatal Vaccination and Infant Monoclonal Antibody Combo Effective RSV Prevention Strategy: JAMA

With the approval of two interventions in 2023—the bivalent prenatal RSV prefusion F protein-based (RSVpreF) vaccine, and the infant monoclonal antibody nirsevimab—understanding their adoption and clinical impact is crucial for public health planning. Evaluating the uptake of the RSVpreF vaccine in pregnant individuals and nirsevimab in infants will provide essential insights into their effectiveness in preventing severe respiratory syncytial virus infections and guide future immunization strategies. Considering this, Christine A. Blauvelt, University of California, San Francisco, and colleagues aimed to analyze the adoption of the prenatal RSVpreF vaccine and infant nirsevimab.

For this purpose, the researchers conducted a retrospective cohort study at a single academic center, examining 647 pregnant individuals eligible for RSVpreF vaccination between 32 and 36 weeks gestation from October 15, 2023, to January 31, 2024, as well as infants eligible for nirsevimab who had not been exposed to prenatal RSVpreF vaccination at least 14 days before birth. By analyzing pregnancies and births during the 2023-2024 RSV season, the study assessed RSVpreF vaccination rates among eligible pregnant individuals and nirsevimab administration before hospital discharge in eligible infants.

Key Findings:

• Among 647 eligible pregnant individuals (mean age 34.6 years), 414 (64.0%) received the RSVpreF vaccine.
• Higher RSVpreF uptake was associated with older maternal age (AOR, 1.09), nulliparity (AOR, 1.84), private insurance (AOR, 2.19), and non-Hispanic ethnicity (AOR, 2.36).
• Receiving any COVID-19 vaccine (AOR, 7.12), the 2023-2024 formula COVID-19 booster (AOR, 5.62), influenza vaccine (AOR, 8.14), or tetanus-diphtheria-pertussis vaccine (AOR, 6.86) was linked to higher RSVpreF uptake.
• Lower RSVpreF uptake was observed among individuals with non-English language preference (AOR, 0.24), Black race (AOR, 0.30), other or unknown race (AOR, 0.48), and multiple gestations (AOR, 0.27).
• Nirsevimab was administered to 183 of 261 eligible infants (70.1%) before hospital discharge.
• Among neonates whose mothers did not receive RSVpreF or standard prenatal vaccines, 40.4% received nirsevimab, while 34.0% of those whose mothers declined infant hepatitis B vaccination received nirsevimab.
• RSV protection exceeded 80% during all study months except October 2023, when prenatal RSV vaccination and nirsevimab were first introduced.
• Preterm delivery occurred in 8.5% of RSVpreF-vaccinated individuals and 18.5% of unvaccinated individuals.
• A nested case-control analysis found no significant link between RSVpreF vaccination and preterm birth (AOR, 1.03).

The researchers found a high uptake of the RSVpreF vaccine and infant nirsevimab, even among those who did not receive routine prenatal or infant vaccines. Their findings showed no significant association between RSVpreF vaccination and preterm birth, reinforcing the safety of this approach.

"The study highlights that an RSV prevention strategy combining prenatal vaccination and infant monoclonal antibody administration achieved substantial adoption and demonstrated reassuring perinatal outcomes, supporting its effectiveness in protecting infants against severe RSV infection," they concluded.

Reference:

Blauvelt CA, Zeme M, Natarajan A, et al. Respiratory Syncytial Virus Vaccine and Nirsevimab Uptake Among Pregnant People and Their Neonates. JAMA Netw Open. 2025;8(2):e2460735. doi:10.1001/jamanetworkopen.2024.60735