FDA Approves RSV Vaccine to Be Given During Pregnancy

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Aug. 22, 2023 – The long-awaited vaccine for RSV that can be given to pregnant people was approved by the FDA on Monday. 

The vaccine is called Abrysvo and can be given between weeks 32 and 36 of pregnancy, and will in turn protect infants from the respiratory virus from birth to 6 months of age. Most children are infected with the highly contagious virus as least once by the time they reach 2 years old. Very young children are at particular risk of severe complications like pneumonia or bronchitis, and in studies the new vaccine reduced that risk by up to 82%. 

Prior to the vaccine’s availability, up to 3% of infants infected with RSV needed to be hospitalized, according to the CDC. Treatments, the CDC says, may include “oxygen, IV fluids (if they aren’t eating and drinking), and mechanical ventilation (a machine to help with breathing). Most improve with this type of supportive care and are discharged in a few days.”

RSV typically causes common cold symptoms, but the virus poses the risk of severe complications that could lead to death among young children and among older people. The CDC estimates 100 to 300 deaths of children under 5 years old and 6,000 to 10,000 deaths of people ages 65 and older are linked to RSV annually.

Earlier this year, the FDA approved drugmaker Pfizer’s Abrysvo vaccine for use in older adults. This is also the first year that an antibody shot is available to be given after birth to prevent severe RSV in infants under 1 year old. 

“We are incredibly grateful to the clinical trial participants and study investigator teams around the world, as well as our Pfizer colleagues, for their commitment to making this vaccine available,” said Pfizer Chief Scientific Officer Annaliesa Anderson, PhD, in a statement. “Today, a long-sought-after goal to deliver a maternal vaccine that will help protect infants six months of age or younger – when they are at greatest risk of possible serious consequences from RSV – has been achieved.”

In its approval announcement, the FDA noted that a dangerous high blood pressure disorder that can occur during pregnancy called preeclampsia occurred in 1.8% of pregnant people who received Abrysvo, compared to 1.4% of those who received a placebo. The FDA also reported that low birth weight and jaundice in infants occurred at a higher rate among the pregnant Abrysvo recipients, compared to the placebo group.

Studies also showed that pregnant people who got the vaccine experienced preterm birth at a rate of 5.7%, compared to a rate of 4.7% among those who got placebo. The FDA called the difference “a numerical imbalance,” but said in the approval announcement that a “causal relationship” could not be established, further noting that people already at high risk of preterm birth were excluded from clinical trials. Pfizer must conduct ongoing studies to monitor the risk of preeclampsia as well as preterm birth, the FDA said.