Pfizer's Abrysvo becomes first maternal RSV shot to protect newborns

Already with an approval in hand for older adults, Pfizer’s Abrysvo has become the first vaccine for pregnant women to protect their newborns against respiratory syncytial virus (RSV).

The FDA has signed off on Abrysvo for women who have been pregnant for 32 to 36 weeks. The shot affords protection to babies for the first six months of their lives.

Pfizer’s vaccine isn’t the first RSV prophylactic for infants. Last month, Sanofi and AstraZeneca scored a green light for Beyfortus in babies up to 24 months of age. But Abrysvo takes the protection a step earlier.

“We’re really excited at the prospect of both having the opportunity to protect babies from their first breath (and) to also be able to see whether we see a decrease in some of these children's lung conditions,” Annaliesa Anderson, Ph.D., senior vice president and head of Pfizer's vaccine R&D, said in an interview with Fierce.

RSV is the leading cause of hospitalization for infants and annually kills around 300 children younger than 5 years of age in the U.S., according to the CDC.

It wasn’t all good news for Pfizer in gaining the maternal endorsement. In May, an FDA advisory committee agreed unanimously that trail results showed Abrysvo’s efficacy supported vaccination in the second and third trimesters of pregnancy. But with the green light, the window of usage was narrowed to just four weeks.

“It’s a global vaccine. We’ll see different licenses and recommendations in different regions,” Anderson said. “So we’ll certainly be getting data on broader vaccination windows that we can look at and look to expand that label with time.” 

The FDA decision to limit the window was likely because Pfizer’s trial of 7,000 pregnant women showed a higher incidence of pre-term birth among those who received the vaccine.

Abrysvo also becomes the first RSV vaccine to gain approval in two different groups. Three months ago, the FDA gave a thumbs up to the shot to protect people 60 and older.

“This complements really nicely the older adult vaccine,” Anderson said. “To be able to bookend the children and the adults at most risk, I think, is really wonderful progress.”

Pfizer’s nod for older adults came weeks after GSK became the first company to gain a green light for an RSV shot as Arexvy was approved for people 60 and older. Both the Pfizer and GSK shots are already available in U.S. pharmacies.

Earlier this month, GSK filed a lawsuit charging that Pfizer’s vaccine infringes four patents related to Arexvy.

Meanwhile, Pfizer is testing Abrysvo in high-risk children between the ages of 2 and 17. It also is testing the shot in immunocompromised adults between the ages of 18 and 59. People with underlying conditions such as asthma, diabetes and COPD, are at higher risk for RSV.

As for Sanofi and AstraZeneca's rival infant prophylactic Beyfortus, the antibody is intended to provide protection for all infants heading into their first RSV season. It's also approved for children who remain vulnerable heading into their second RSV season.

The RSV season typically starts in the late fall and peaks in the winter, so this upcoming season will see several new product launches vying for market share in a potentially lucrative field.