The Food and Drug Administration approved Abrysvo, Pfizer’s respiratory syncytial virus (RSV) vaccine, for use in pregnant individuals to prevent lower respiratory tract disease (LRTD) and severe LRTD caused by RSV in infants.

The approval, which was announced Monday evening, makes the vaccine the first one available for pregnant individuals between 32 and 36 weeks of gestational age. Abrysvo was approved by the FDA earlier this year to prevent RSV in people over the age of 60.

“This approval provides an option for healthcare providers and pregnant individuals to protect infants from this potentially life-threatening disease,” Peter Marks, MD, PhD, the director of the FDA’s Center for Biologics Evaluation and Research, said in a statement.

Abrysvo is a single dose injection that protects infants from RSV, the most common cause of bronchiolitis and pneumonia. The National Coalition for Infant Health calls RSV the leading cause for hospitalization of babies under the age of one.

According a clinical study Pfizer conducted to evaluate the effectiveness of Abrysvo preventing LRTD and severe LRTD caused by RSV in infants born to people who were vaccinated while pregnant, the shot reduced the risk of severe LRTD by 82% within 90 days after birth and just over 69% within 180 days after birth.

The most common reported side effects of the vaccine were pain at the injection site, headache, muscle pain and nausea.

In a separate statement, Pfizer welcomed the approval as a “significant milestone for the scientific community and for public health.”

“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,” Annaliesa Anderson, PhD, SVP and chief scientific officer, vaccine research and development at Pfizer, said in a statement

The pharma giant stated that it also initiated two additional clinical trials evaluating Abrysvo in children at higher risk of RSV disease and adults between the ages of 18 and 60 who have underlying medical conditions.

The approval for Abrysvo in pregnant people gives Pfizer a leg up in the increasingly competitive RSV vaccine market.

GSK made the first splash this spring when the FDA approved GSK’s Arexvy for preventing RSV in people over the age of 60. GSK’s approval was based on the strength of its Phase 3 trial data, which were published in the New England Journal of Medicine.

Shortly thereafter, Abrysvo got the regulatory go-ahead for treating people over the age of 60. 

About a month-and-a-half later, the FDA approved Beyfortus, the vaccine jointly developed by AstraZeneca and Sanofi to prevent LRTD caused by RSV in newborns and infants up to 2 years old.

The FDA’s expanded approval of Abrysvo comes ahead of the 2023/24 RSV season, which expects to be closer to the pre-pandemic normal, though they have cautioned that case numbers will probably be higher. 

To that end, drugmakers are lining up supplies to meet the expected demand. GSK said last week that Arexvy has arrived at major U.S. pharmacies.