FDA approves Pfizer’s RSV vaccine to protect infants
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Key takeaways:
- The FDA approved the first RSV vaccine to protect infants from RSV.
- The vaccine is administered to pregnant people at 32 through 36 weeks’ gestation.
The FDA has approved the first vaccine for pregnant people to protect infants from respiratory syncytial virus.
The approval came 3 months after FDA advisors voted unanimously that data showed the vaccine (Abrysvo, Pfizer) prevented RSV in infants during their first 6 months after birth when given to pregnant patients in the second or third trimester.
The FDA approved the vaccine for use as a single intramuscular injection at 32 through 36 weeks’ gestational age.
Abrysvo and another RSV vaccine made by GSK became the world’s first two licensed RSV vaccines when the FDA approved them for older adults earlier this year.
RSV is a common respiratory infection that can cause serious illness, especially in infants and older adults. It is the leading cause of infant hospitalizations in the United States, according to the CDC.
A surge of RSV stretched hospital capacity late last year, and the virus was part of a winter tripledemic of respiratory diseases, alongside COVID-19 and influenza. Vaccines for all three will be available this fall and winter.
“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,” Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research, said in a press release. “This approval provides an option for health care providers and pregnant individuals to protect infants from this potentially life-threatening disease.”
Phase 3 data presented by Pfizer showed that at 90 days after birth, the vaccine’s efficacy was 57.1% (99.5% CI, 14.7%-79.8%) against RSV-positive, medically attended lower respiratory tract illness (MA-LRTI) and 81.8% (99.5% CI, 40.6%-96.3%) against RSV-positive severe MA-LRTI in infants.
One adverse event noted in documents prepared for the FDA advisors’ meeting was preterm birth — or birth at less than 37 weeks’ gestation — which was reported in 5.7% (95% CI, 4.9%-6.5%) of infants in the trial’s vaccine group and 4.7% (95% CI, 4.1%-5.5%) of infants in a placebo group. The difference, according to the FDA document, was not statistically significant.
This, along with the other noted adverse event of low birth weight, was cited as a concern by members of the FDA advisory committee that recommended the vaccine’s approval. The committee voted 14-0 in agreement that the data showed the vaccine is effective, but four members voted “no” on a second question on whether data demonstrated it had an adequate safety profile.
Committee member Capt. Amanda Cohn, MD, director of the CDC’s Division of Birth Defects and Infant Disorders, voted “yes” to both questions during the May meeting.
“To me, enrolling more people in these clinical trials and having really strong post-licensure evaluations because you still want to check on all outcomes will be what we need to reassure the public and to give pregnant women the data that they need to make the decision to get vaccinated,” Cohn said at the time.
According to the FDA, the most commonly reported side effects by pregnant people who received the vaccine were pain at the injection site, headache, muscle pain and nausea.
“In addition, although not commonly reported, a dangerous 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 placebo,” the release said. “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 approval is the latest in a series of recent regulatory decisions in favor of preventive measures against RSV. In addition to the vaccine approvals, the CDC recommended this month that infants be immunized with a monoclonal antibody against RSV.
Abrysvo will next be reviewed by the CDC’s Advisory Committee on Immunization Practices to establish federal recommendations on its use to protect infants during their initial RSV seasons.
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