Report on maternal RS virus vaccination

Abstract

We investigated the safety of recombinant respiratory syncytial virus vaccine (AbrysvoⓇ) for pregnant women based on the vaccination history at our hospital.

The backgrounds of pregnant women who received this vaccine at our hospital from June to November 2024 and the perinatal outcomes of mothers and children who gave birth by December 5 of the same year were retrospectively examined from medical records, with mothers and children who gave birth at our hospital in 2023 as controls. We analyzed singleton pregnancies. Analysis was performed using chi-square test or t-test.

A total of 280 pregnant women received this vaccine during this period, and no adverse events requiring medical treatment at the time of vaccination occurred.

The maternal age ranged from 25 to 47 years old. The vaccination period was 28 to 36 weeks, with 214 cases (78.6%) being primiparous and 61 cases (21.4%) being multiparous. The 206 cases who gave birth after vaccination were compared with the 1,431 cases in 2023. There was no change in the mode of delivery between the vaccinated and control groups, and there was no significant increase in emergency cesarean sections. There were no significant differences between the two groups in the rate of premature birth, the incidence of hypertensive disorders of pregnancy, or the amount of bleeding during delivery. Although it takes two weeks after vaccination for the infants to acquire sufficient immunity, eight cases who vaccinated at 35 and 36 weeks of gestation delivered before two weeks after vaccination. There were no differences between the two groups in the birth weight of the infants, Apgar score of less than 7 at 5 minutes after　birth, blood gas of umbilical artery pH less than 7.1, or NICU admission rate. No adverse events were observed during vaccination, and no events　to be considered occurred during the perinatal period.