FDA Alert

FDA Approves First RSV Vaccine For Pregnant Individuals

Anthony Calabro, MA

The FDA approved the first-ever vaccine authorized for use in pregnant individuals to prevent lower respiratory tract disease (LRTD) and severe LRTD caused by respiratory syncytial virus (RSV) in infants from birth through 6 months of age. The vaccine is to be administered as a single-dose injection into the muscle and is approved for use specifically between the 32nd and 36th weeks of gestational age of pregnancy.

In May of this year, the FDA approved the vaccine for the prevention of LRTD caused by RSV in those 60 years of age and older.

Peter Marks MD, PhD, the director of the FDA's Center for Biologics Evaluation and Research, highlighted the importance of this approval for use in pregnant individuals.

“RSV is a common cause of illness in children, and infants are among those at highest risk for severe disease, which can lead to hospitalization,” Dr Marks said. “This approval provides an option for health care providers and pregnant individuals to protect infants from this potentially life-threatening disease.”

Although RSV is a highly contagious virus that affects individuals of all ages, it is the most common cause of LRTD in infants globally. The risk of RSV-associated LRTD is most common during the first year of life.

Researchers conducted a clinical study to evaluate the vaccine’s effectiveness in preventing LRTD and severe LRTD caused by RSV in infants born to individuals who were vaccinated during pregnancy. The study included approximately 3500 pregnant individuals who received the vaccines and approximately 3500 who received a placebo. Among those who received the vaccine, the vaccine led to an 81.8% reduction in the risk of severe LRTD within 90 days after birth. Within 180 days after birth, the reduction was 69.4%. Furthermore, in a subgroup of pregnant individuals who were between 32- and 36-weeks gestational age, the vaccine reduced the risk of LRTD by 34.7% and the risk of severe LRTD by 91.1% within 90 days after birth. Within 180 days after birth, the vaccine decreased the risk of LRTD by 57.3% and of severe LRTD by 76.5% when compared with the placebo group.

Regarding the safety of the vaccine, researchers conducted two studies. In the first, researchers compared about 3600 pregnant individuals who received a single dose of the vaccine with 3600 pregnant individuals who received placebo. In the second, about 100 pregnant individuals received the vaccine vs about 100 who received placebo. Pain at the injection site, headache, muscle pain, and nausea were the most common adverse effects. However, pre-eclampsia occurred in 1.8% of individuals receiving the vaccine vs 1.4% of the placebo group.

Additionally, low birth weight and jaundice in infants occurred at a higher rate in the vaccine group compared with the placebo group. Finally, the Prescribing Information includes a warning about a slight increase in preterm births for those who took the vaccine (5.7%) vs those who received placebo (4.7%).

As a result of the safety evaluation, the FDA is requiring postmarketing studies to investigate the level of serious risk of preterm birth and to assess hypertensive disorders of pregnancy, including pre-eclampsia.


FDA Approves First Vaccine for Pregnant Individuals to Prevent RSV in Infants. News release. The US Food and Drug Administration; August 21, 2023. Accessed August 24, 2023.