“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,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research. “This approval provides an option for health care providers and pregnant individuals to protect infants from this potentially life-threatening disease.”
Abrysvo is administered as a single-dose injection into the muscle. This vaccine is also one of the vaccines the FDA approved in May, and the CDC recommended in June, for adults 60 years of age and older.
Studies weigh effectiveness, safety
Clinical studies evaluated the safety and effectiveness of the vaccine. In one study among 3,500 pregnant individuals who received Abrysvo, compared to 3,500 pregnant individuals who received a placebo, Abrysvo reduced the risk of severe lower respiratory tract disease by 81.8% within 90 days after birth, and by 69.4% within 180 days after birth.
“It doesn’t prevent illness period, but it prevents the babies from getting really sick from RSV,” said Dr. Yangshu Linda Pan, of Premier Health’s Lifestages Centers for Women.
RSV can cause illness in people of all ages but may be especially serious for infants and older adults, according to the CDC. Pregnant women also have decreased immune systems.
“Anyone can get RSV at any point, and generally, at least for the flu, pregnant people who get the flu are much higher risk of getting a lot sicker from the flu,” Pan said.
The most commonly reported side effects by pregnant women who received Abrysvo were pain at the injection site, headache, muscle pain and nausea.
In addition, although not commonly reported, a hypertensive disorder, known as pre-eclampsia, occurred in 1.8% of pregnant individuals who received Abrysvo, compared to 1.4% of pregnant individuals who received the placebo. In the safety studies, low birth weight and jaundice in infants occurred at a higher rate in the pregnant Abrysvo recipients compared to pregnant placebo recipients.
The research is still new, Pan said, and the CDC and the American College of Obstetricians and Gynecologists have not yet made a recommendation on this new vaccine for pregnant individuals.
“Right now, I think we’re kind of cautiously optimistic, but have not made a particular statement about this vaccine yet,” Pan said.
The FDA is requiring the company to conduct post-marketing studies to assess the signal of serious risk of preterm birth and to assess hypertensive disorders of pregnancy, including pre-eclampsia.
Differing RSV vaccines, immunizations
In May, the FDA approved the first two vaccines, Arexvy and Abrysvo, for prevention of RSV lower respiratory tract disease for use in adults 60 and older. The CDC also provided recommended use of the vaccines for adults in consultation with their doctors.
For both products, vaccination with a single RSV vaccine dose demonstrated moderate to high efficacy in preventing symptomatic lower respiratory tract disease, according to the CDC.
The CDC is also recommending Nirsevimab (trade name Beyfortus), which is a new RSV immunization for infants younger than 8 months old that is expected to be available this fall. This immunization is not a vaccine, but is a long-acting monoclonal antibody product that provides passive immunity. The CDC says this shot has been shown to reduce the risk of both hospitalizations and health care visits for RSV in infants by about 80%.
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