Study Confirms Abrysvo RSV Vaccine Safe During Late Pregnancy

Pregnant women receiving the respiratory syncytial virus (RSV) vaccine to protect their newborns face no increased risk, according to recent research. The study, published in the journal JAMA Network Open, revealed that vaccination during late pregnancy did not correlate with higher rates of preterm births or other complications.

The research found no significant difference in preterm birth rates between vaccinated women (5.9%) and unvaccinated women (6.7%). This evidence supports the safety of Pfizer's Abrysvo vaccine. "Real-world evidence bolsters the confidence in the safety of this vaccine during pregnancy," stated Dr. Moeun Son, lead author and associate professor of obstetrics and gynecology at Weill Cornell Medicine. "Data from various populations now indicate no increased risk of preterm birth."

RSV is a significant health concern, with up to 80,000 children under five hospitalized yearly in the United States and up to 300 fatalities, according to the U.S. Centers for Disease Control and Prevention (CDC). Following clinical trials, the U.S. Food and Drug Administration (FDA) approved the Abrysvo vaccine last August for women between 32 and 36 weeks of pregnancy. A CDC panel also recommended the vaccine for eligible pregnant women during RSV season, which spans from September to January.

This single-dose vaccine facilitates the production of protective antibodies that are transferred from the mother to the fetus via the placenta. For the study, Dr. Son and her colleagues evaluated pregnancy outcomes among 1,026 vaccinated and 1,947 unvaccinated women treated at two New York City hospitals. They assessed various outcomes, including preterm birth rates, stillbirths, low birth weight, NICU admissions, respiratory distress in NICU infants, low blood sugar, and sepsis.

Dr. Son, also a maternal-fetal medicine doctor at New York-Presbyterian/Weill Cornell Medical Center, emphasized, "Patients and clinicians can trust that vaccination during pregnancy is a safe measure to protect infants from severe RSV infections."

To ensure the reliability of their findings, the researchers employed three different statistical analyses. While they noted a slightly elevated risk of high blood pressure during pregnancy in vaccinated women in one of the analyses, further research is needed to determine if this is a significant concern or a statistical anomaly.

"These questions will continue to be investigated in future studies," Dr. Son said in a Weill Cornell Medicine news release. The study also noted that 35% of pregnant women at the two hospitals were vaccinated, nearly double the national average of 18%. Vaccinated women were more likely to have health insurance or to have undergone in vitro fertilization, while Black women, those with public insurance, and those with fewer prenatal visits were less likely to receive the vaccine.

The next phase of the research aims to engage with various communities to understand the reasons behind vaccination hesitancy or barriers to access. The goal is to address these concerns before the RSV season starts in September. Dr. Son concluded, "We want to ensure everyone who could benefit from the vaccine has access to it."