FDA Approves RSV Vaccine for Pregnant Women to Protect Newborns

FDA Approves RSV Vaccine for Pregnant Women to Protect Newborns

New Vaccine Approved to Protect Newborns from Respiratory Syncytial Virus (RSV)


The U.S. Food and Drug Administration (FDA) has recently approved a new vaccine called Abrysvo, which may provide pregnant women with a powerful tool to protect their infants from respiratory syncytial virus (RSV). This vaccine, awaiting further authorization from the U.S. Centers for Disease Control and Prevention (CDC), is specifically designed to safeguard newborns from birth through their first 6 months of life against the often severe respiratory illness caused by RSV.

Dr. Peter Marks, the director of the FDA’s Center for Biologics Evaluation and Research, stated, “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. This approval provides an option for health care providers and pregnant individuals to protect infants from this potentially life-threatening disease.”

RSV is a highly contagious virus that can infect people of all ages. It is the most frequent cause of lower respiratory tract illness in infants worldwide, typically appearing in fall and winter. While RSV usually results in cold-like symptoms, it can lead to more serious illnesses such as pneumonia and bronchiolitis. The FDA warns that the first year of life poses the highest risk for infants. In fact, RSV is the leading cause of infant hospitalizations in the United States, according to the CDC.

Until now, the only available protection against RSV for infants was a lab-made antibody shot called Beyfortus. However, Abrysvo brings new hope to parents and healthcare providers as it is estimated that the vaccine, if administered to enough women, could prevent 320,000 infant doctor visits and 20,000 hospitalizations each year.

Abrysvo, developed by Pfizer, will be given as a single-dose injection into the muscle. This vaccine is already approved by both the FDA and CDC to prevent RSV-caused illness in people aged 60 and older. Clinical trials have demonstrated the safety and effectiveness of Abrysvo.

In one study, approximately 3,500 pregnant women received Abrysvo, while another 3,500 received a placebo. The trial showed that the vaccine reduced the risk of severe illness by almost 82% within three months after birth, and by about 69% by the time the infant reached 6 months of age. Another subgroup of 1,500 pregnant individuals who received Abrysvo exhibited a 35% reduction in the risk of respiratory illness, and a staggering 91% reduction in the risk of severe lower respiratory tract disease (LRTD) within three months after birth compared to those who received the placebo. By the time a baby is 6 months old, Abrysvo reduced the risk of RSV respiratory illness by about 57%, with a 76.5% reduction for severe illness when compared to the placebo, according to the FDA.

In terms of safety, two studies evaluated Abrysvo. The first study included approximately 7,200 women, with half of them receiving the vaccine. The second study involved about 200 pregnant women, of which half received Abrysvo. Side effects observed included pain at the injection site, headache, muscle pain, and nausea. It is worth noting that a hypertensive disorder of pregnancy called pre-eclampsia occurred in 1.8% of pregnant individuals who received Abrysvo, compared to 1.4% who received the placebo. In addition, low birth weight and jaundice were reported at a higher rate in infants born to mothers who received Abrysvo.

Prescribing information for Abrysvo will include a warning about a numerical imbalance in preterm births (5.7% in Abrysvo recipients versus 4.7% in placebo recipients). The data is insufficient to establish a causal relationship between the vaccine and preterm births, but it serves as a cautionary signal for healthcare providers, as highlighted by the FDA. Pfizer will be required to conduct more studies focused on evaluating the risks of preterm birth and pre-eclampsia associated with Abrysvo.

The recent approval of Abrysvo under FDA’s Fast Track and Breakthrough Therapy designations signifies a significant step forward in protecting newborns from RSV. With further authorization from the CDC, this vaccine has the potential to make a substantial impact on reducing the burden of RSV-related illnesses for infants.

Sources: – U.S. Food and Drug Administration, news release, Aug. 21, 2023 – Associated Press


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