FDA Approves RSV Vaccine for Pregnant People To Protect Newborns

Trial results showed the vaccine was nearly 82% effective at protecting infants in their first 90 days.

Fact checked by Sarah Scott

Parents of young children are acutely aware of a triple threat of respiratory viruses circulating as winter approaches: The flu, COVID-19, and respiratory syncytial virus (RSV).

Children ages six months and up are currently eligible for vaccines that provide strong protections against severe outcomes, including hospitalization and death, for the flu and COVID-19. But now there's a new vaccine that can help protect babies from that third virus—RSV—when it's given to their pregnant parent between 32-36 weeks of gestational age.

On August 21, 2023, the Food and Drug Administration (FDA) approved Pfizer's vaccine, ABRYSVO™, or Respiratory Syncytial Virus Vaccine (RSV Vaccine). It is the first maternal vaccine approved in the U.S. to protect infants from birth through six months of life against lower-respiratory tract disease (LRTD) and severe LRTD because of RSV. Trial results showed it was nearly 82% effective at protecting infants from RSV in their first 90 days and nearly 70% effective for 180 days.

Between 58,000 and 80,000 children under 5 are hospitalized with RSV each year, and 100 to 300 die, according to estimates from the Centers for Disease Control and Prevention (CDC).

“I think the FDA approval of the Pfizer maternal RSV vaccine is an incredibly exciting breakthrough against a devastating respiratory virus that has been a leading cause of hospitalization in infants and children for decades,” says Elizabeth Schlaudecker, MD, the medical director of the Division of Infectious Diseases at Cincinnati Children’s who served as the investigator at Cincinnati Children’s for the Pfizer maternal RSV vaccine clinical trial.

The FDA’s approval comes after a Phase 3 clinical trial of more than 14,000 trial participants consisting of more than 7,000 pregnant people and their infants. The Phase 3 trial evaluated the vaccine’s safety and efficacy in protecting infants from LRTD and severe LRTD because of RSV in babies born to healthy, vaccinated people during pregnancy.

“Vaccines undergo a three-stage clinical trial process—Phases 1, 2, and 3, before FDA approval,” explains Dr. Schlaudecker. “During Phase 3 clinical trials, when thousands of people are receiving the trial vaccine, the FDA looks at the data about the safety and quality of the vaccine, as well as the company’s proposed manufacturing process for the vaccine.”

The New England Journal of Medicine published these results in April.

“When the mother receives the vaccine during pregnancy, the vaccine is 81.8% effective against any medically attended severe lower respiratory tract illness in the infant for the first 90 days of life and nearly 70% effective in the first 180 days of life,” says Dr. Schlaudecker.

In an interview with Parents, Sarah Pachtman, MD, the associate director of maternal/fetal medicine, inpatient services at LIJ Medical Center, compared it to the t-DAP vaccine. That immunization is given to pregnant people in their third trimester and ultimately provides protection against whooping cough for the newborn until they can get their shot between four and eight weeks of life.

Pfizer announced it had enough data to submit the vaccine for approval in late 2022, though experts had cautioned that it would not be available during the 2022-23 "sick season." Last year’s RSV season saw a surge in cases. In fact, during a media briefing in November, the CDC mentioned that some regions were seeing RSV infection numbers in November, typically reserved for peak season in December and January.

RSV usually presents as flu-like symptoms, says Dr. Pachtman.

Jennifer L. Lighter, MD, a pediatric infectious disease specialist with NYU Langone Health, adds that most children get the virus before they are 2. But it can be risky to infants, premature babies, and children with heart and lung disease.

“We need a universal vaccine at this point because there is significant morbidity in the U.S. and worldwide," Dr. Lighter says.

Currently, the most at-risk babies, including those with heart and lung diseases or born at 32 weeks of gestation or earlier, can receive monoclonal antibody treatment once per month. In its clinical trials back in the late 1990s, Palivizumab reduced hospitalization for RSV by about 55%, but it's not widely available for all infants.

But soon, Abrysvo should be widely available. A representative for Pfizer noted that the CDC’s Advisory Committee on Immunization Practices (ACIP) will need to weigh in first, and the next regularly scheduled meeting is slated for October 25-27, 2023. Pfizer is hopeful there will be sufficient supply for maternal and older adult populations for this year’s peak RSV season.

Once ABRYSVO is made available, Dr. Schlaudecker is encouraging pregnant people to get the vaccine. “I recommend this vaccine in pregnant people, as it is safe in mothers and infants and effective against severe illness in infants,” Dr. Schlaudecker says.

Still, as we saw during the COVID vaccine rollout, misinformation may cause hesitancy. Dr. Schlaudecker says your healthcare providers are there to help you sort through the information. “I recommend talking to your primary care physician or obstetrician about this vaccine if you have any further questions,” she says, adding that Cincinnati Children's has vaccine resources.

Related: RSV in Infants: Everything Parents Need To Know

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Read the original article on Parents.