A panel of outside advisers to the Food and Drug Administration (FDA) narrowly voted in favor of the country’s first RSV vaccine for older adults, paving the way forward for the shot to be approved by the full agency.

The panel voted 7-4 with one abstention that current data support the vaccine’s safety, and voted 7-4 with one abstention in favor of its efficacy, saying that the vaccine adequately protects older adults from lower respiratory tract disease related to RSV.

In August, Pfizer announced that the vaccine was more than 85 percent effective in preventing severe lower respiratory tract illness in older adults, as marked by three symptoms. 

In healthy adults and older children, RSV typically causes mild, cold-like symptoms that go away with moderate rest and self-care. But it can result in severe illness in infants and older adults. 

RSV causes between 60,000 and 160,000 hospitalizations annually for adults older than 65 in the U.S., and 6,000 to 13,000 deaths, according to federal statistics.

Like the flu, RSV season usually occurs during colder weather, though it hit unusually hard and early this year, contributing to a wave of respiratory infections that overwhelmed hospitals nationwide.  

There is no vaccine for RSV in either adults or children.

FDA usually follows the panel’s recommendations, but it is not required to. The agency in December said it granted Pfizer priority review, which reduces the approval timeline by four months. The end of the review period is expected to be May 2023, Pfizer said.

Panel members expressed concern that the clinical trials did not include many cases of RSV among people who have other underlying health problems, putting them at greater risk. There were also concerns over the durability of protection.

“These were very stable patients, very — selected to be healthy, that produce good immune responses but were really not the ones that have the efficacy endpoints that are so necessary for decisionmaking,” said Steven Pergam, an infectious disease expert and medical director who voted “no” on the efficacy question.

Panelists who voted “no” on the vaccine’s safety were generally worried about its potential association with Guillain-Barré syndrome, a rare neurological disorder. 

Pfizer said the reaction could have been due to other issues, but FDA flagged it as “an important potential risk” that would need to be closely tracked and studied further if the vaccine is approved. 

While Pfizer’s was the first such shot to be voted through the advisory committee, a second one could follow on Wednesday, as the same panel meets to discuss the safety and efficacy of an RSV shot from GlaxoSmithKline (GSK) for people ages 60 and older.

Like Pfizer, GSK was also granted priority review for its vaccine candidate. GSK’s vaccine was about 83 percent effective in preventing lower respiratory tract disease in people aged 60 and over, and 94 percent effective in preventing severe disease.