The FDA approved the first prenatal vaccine to protect newborns against respiratory syncytial virus (RSV) on Monday, which experts touted as a “major triumph.”
Pregnant people in their late second or third trimesters can receive Pfizer’s Abrysvo, which helps protect babies under six months old from developing RSV-related lower respiratory tract disease, according to Pfizer.
“Newborns and young infants—whose immune systems are still developing and are not yet strong enough to defend against infections—may now be protected from RSV from the moment of birth through maternal immunization,” Eric Simões, a clinical professor of pediatrics and infectious diseases at the University of Colorado School of Medicine and Children’s Hospital Colorado, said in a statement.
RSV infection usually causes mild cold-like symptoms, but in higher-risk groups such as preemies, it can lead to severe lower respiratory tract diseases like pneumonia or bronchiolitis, according to the Centers for Disease Control and Prevention (CDC). Each year RSV is linked to 58,000–80,000 hospitalizations nationwide for children under the age of five, making it one of the leading causes of infant hospitalization in the country, the CDC said.
The FDA first approved Abrysvo in May for use in adults over the age of 60 who are at high risk for RSV-related complications, Healthcare Brew previously reported.
Pfizer’s RSV vaccine was found to be 81.8% effective at preventing severe disease in infants under three months old, and 69.4% effective in those under six months old, an April 2023 study of over 7,300 pregnant individuals found.
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The vaccine may come with some side effects.
About 1.8% of pregnant individuals who received Abrysvo developed preeclampsia, a potentially life-threatening high blood pressure condition, compared with 1.4% of those who received the placebo, according to the FDA.
During the trials, pregnant participants who received the vaccine also had a higher rate of preterm births than the placebo group—5.7% versus 4.7%, respectively. Those results prompted the FDA to add a prescribing label on Abrysvo that warns providers against administering the vaccine before 32 weeks gestation. Still, those rates are below the prevalence of preterm births in the US, the CDC found.
Nonetheless, the FDA added that “the available data [is] insufficient to establish or exclude a causal relationship between preterm birth and Abrysvo.”
The vaccine is expected to be available later this year following a CDC advisory committee meeting, at which officials are to give their official recommendations, NBC News reported.
While RSV infections typically peak during the winter, some states such as Georgia and Florida are already seeing the number of RSV cases increase, epidemiologist Caitlin Rivers, who is also an assistant professor and senior scholar at the Johns Hopkins Bloomberg School of Public Health, wrote in her newsletter Force of Infection.
Last month, the FDA also approved AstraZeneca and Sanofi’s Beyfortus, an injectable monoclonal antibody that can help prevent RSV-related lower respiratory tract disease in children up to two years old.