The approval of the non-adjuvanted bivalent respiratory syncytial virus prefusion F (RSVpreF) protein subunit vaccine for pregnant individuals during the 2023-2024 RSV season marked a significant step in maternal and neonatal health. Clinical data on its safety and perinatal outcomes were sparse at the time, however, a retrospective observational cohort study conducted at two New York City hospitals sought to bridge this knowledge gap by evaluating the association between prenatal RSVpreF vaccination status and various maternal and neonatal outcomes. Results were published in the Journal of the American Medical Association.
This study included 2973 eligible pregnant women who delivered singleton gestations at 32 weeks’ gestation or later between September 22, 2023, and January 31, 2024. The median age of participants was 34.9 years.
In the cohort, 34.5% had electronic health record evidence of RSVpreF vaccination before delivery, a significantly higher rate than the national average of 17.8% reported by the CDC. The mean gestational age at vaccination was 34.5 weeks. The study found no significant association between prenatal RSVpreF vaccination and increased risk of preterm birth (PTB), defined as delivery before 37 weeks’ gestation.
In addition to PTB, the study examined several other maternal and neonatal outcomes. The incidence of hypertensive disorders of pregnancy (HDP), small-for-gestational-age (SGA) birth weight, stillbirth, neonatal intensive care unit (NICU) admission, respiratory distress, jaundice, hypoglycemia, and sepsis were analyzed. Notably, there was an increased risk of overall HDP in the vaccinated group in the time-dependent model. However, no significant differences were observed in other outcomes, suggesting the overall safety of the vaccine during pregnancy.
The findings from this study provide critical real-world evidence supporting the safety of the RSVpreF vaccine for pregnant individuals. Dr. Moeun Son, professor of obstetrics and gynecology at Weill Cornell Medicine and the study's lead author, emphasized to Medical Dialogues, "The real world evidence provides an additional layer of confidence about the safety of this vaccine during pregnancy."
In conclusion, this study provides reassuring evidence that prenatal RSVpreF vaccination does not increase the risk of preterm birth and is generally safe for pregnant individuals. While an increased risk of HDP was observed, further investigation is necessary to understand this association fully.
Sources: Journal of the American Medical Association, Medical Dialogues
