After hours of deliberation over safety concerns, a Food and Drug Administration advisory panel on Wednesday recommended approval of a second vaccine for the respiratory syncytial virus in older adults, advancing the first shots against a respiratory illness that can be deadly for the very young and the very old.
Over two days this week, the panel debated and then voted in favor of two vaccines, one by Pfizer and one by GSK (GlaxoSmithKline), that would become available for adults 60 and older.
The panels made their recommendations to the agency, which typically abides by advisory committee decisions and could grant formal approval within months.
The F.D.A. estimates that R.S.V. is associated with 6,000 to 10,000 deaths each year in adults 65 and older and at least 60,000 hospitalizations in that group. It is a leading killer of children worldwide. This winter, R.S.V. contributed to the tripledemic also involving flu and Covid cases that swamped children’s hospitals and some I.C.U. wards. The caseloads have eased off recently.
Advisers did not view approval as a simple choice, though. They debated the benefits of a vaccine for R.S.V. patients who overwhelmingly avoided hospitalization against the very few, but concerning, reports of autoimmune conditions like Guillain-Barré syndrome that emerged shortly after the shots were administered.
On Tuesday, the panel voted in favor of the Pfizer vaccine by 7 to 4, with one abstention, on its safety and efficacy. On Wednesday, it voted 10 to 2 in favor of the GSK vaccine’s safety and unanimously on the shot’s efficacy.
About 34,000 patients were studied in Pfizer’s trial, with half getting a placebo, according to an F.D.A. summary of the data. The vaccine was deemed nearly 67 percent effective in preventing R.S.V.-related lower respiratory tract illness, which can lead to pneumonia. That vaccine was nearly 86 percent effective in treating the disease with three or more symptoms, according to the data.
The GSK vaccine was nearly 83 percent effective in lower respiratory tract illness in a study of about 25,000 patients — half on the vaccine and half on a placebo, according to data the company provided to the F.D.A. No R.S.V. deaths were reported among the patients in the GSK study.
Several panel members expressed concerns about side effects reported with each vaccine. After seven days, one patient who received the Pfizer vaccine developed Guillain-Barré syndrome, a condition where the immune system attacks the nervous system (but not the spine or brain). The case was considered life-threatening, F.D.A. records show, though a “potentially confounding factor” was that the patient had suffered a heart attack the day before the condition developed.
Another Pfizer vaccine recipient developed Miller Fisher syndrome, which is considered to be a type of Guillain-Barré, eight days after getting the shot. That patient, from Japan, reported double vision and a tingling or burning feeling in her palms and the soles of her feet. Her symptoms were mostly resolved within 41 days, the F.D.A. records said.
The two cases in the Pfizer study put the rate of the condition at about one in 9,000, even though it is typically about one in 100,000, according to Dr. Hana El Sahly, chairwoman of the vaccine advisory committee and a professor of virology at Baylor College of Medicine. “So this is major,” Dr. El Sahly said.
Dr. Marie Griffin, a health policy professor at Vanderbilt University, said the Pfizer vaccine was difficult to evaluate given the low incidence of severe infections among those in the trial.
“I think the benefit for relatively healthy, older people — you have to consider that — is not that great,” Dr. Griffin said. “Compared to a possible high risk of a very severe outcome.”
One recipient of the GSK vaccine, who was 78 and from Japan, also developed Guillain-Barré nine days after getting the vaccine; she went on to spend six months in a rehabilitation hospital. The company and the F.D.A. considered the case to be related to the vaccine.
Two recipients of the GSK vaccine, both 71 and from South Africa, developed acute disseminated encephalomyelitis, a neurological disorder with symptoms including weakness and loss of vision. One case resulted in death. The company and the F.D.A. considered the cases “possibly related” to the vaccine, noting that both patients also received a flu vaccine at the same time as the R.S.V. shot.
Watching the safety of the vaccines after they are approved will be important, said Dr. Henry Bernstein of the Zucker School of Medicine at Hofstra University, and should be considered against the background that the effort to create an R.S.V. vaccine has gone on for years.
“I don’t know that there’s a rush to get this to market if we’re going to take two steps forward, and three steps back as far as public health and optimizing vaccination rates,” Dr. Bernstein said.
Pfizer and GSK said they would conduct continuing safety monitoring of the vaccines if they were approved by the F.D.A.
Vaccine experts from the Centers for Disease Control and Prevention examined the study data and determined that in one year, more than 21,000 people 65 and older would need to take the GSK vaccine to prevent one R.S.V. death; the number was nearly 25,000 for the Pfizer shot. They concluded that the data supported use of the vaccines for patients in that age group (but not in patients 60 and older).
A C.D.C. survey of nearly 600 people 60 and older showed that 68 percent would “definitely” or “probably” get an R.S.V. vaccine if an option approved by the F.D.A. were available. Nearly 10 percent more said they would get the shot if a health care provider recommended it.