- A majority of the FDA’s advisers said the safety and efficacy data support use of Pfizer’s RSV vaccine in adults age 60 and older.
- But several FDA advisers said it could be a significant safety concern after two people developed Guillain-Barre syndrome out of about 20,000 vaccine recipients.
- Other advisers were frustrated by the lack of effect data on people with weak immune systems and residents of nursing homes.
Blood test for respiratory syncytial virus (RSV) test
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The Food and Drug Administration’s independent advisers on Tuesday recommended Pfizer’s RSV vaccine for adults age 60 and older, despite safety concerns after two people who received the shot developed a rare neurological disorder.
A majority of FDA committee members supported the vaccine, but they battled in separate votes over whether the safety and efficacy data are sufficient to support an approval from the agency. The FDA is expected to make a decision in May.
There is currently no vaccine to protect older adults from respiratory syncytial virus, which kills thousands of seniors each year. Pfizer’s shot could be the first to get FDA approval.
In the first vote Tuesday, seven members of the FDA committee said the safety data was sufficient for an approval, while four said it was not and one member abstained.
The vote followed concerns by the FDA and among advisory committee members about two cases of Guillain-Barre syndrome among about 20,000 vaccine recipients. Guillain-Barre is a rare neurological disorder in which the body’s immune system mistakenly attacks the nerves.
The symptoms can vary from short-term weakness to paralysis. Most patients, even those with severe cases, recover.
In the second vote, seven committee members said the data on vaccine effectiveness was sufficient, while four said it was not, and one member abstained.
The shot was about 86% protective against lower respiratory tract disease with three or more symptoms, and 66.7% effective against the same condition with two or more symptoms, according to an FDA review of Pfizer’s data. Symptoms included wheezing, shortness of breath, rapid and shallow breathing as well as mucus production.
In adults age 65 and older, RSV causes 6,000 to 10,000 deaths and 60,000 to 160,000 hospitalizations per year, according to the Centers for Disease Control Prevention. The risk of hospitalization increases with age, and adults aged 70 and over are more vulnerable.
Among adults of all ages hospitalized with RSV, 19% require intensive care and 4% die, according to CDC data from three seasons. Mortality is highest among the elderly.
Pfizer’s vaccine contains both strains of RSV, which circulate simultaneously in autumn and winter. The syringe is administered as a single dose of 120 micrograms.
The FDA considers the two Guillain-Barre cases under trial to be possibly linked to the vaccine, said Dr. Nadine Peart Akindele, an agency official. The FDA has asked Pfizer to develop a safety study that will monitor Guillain-Barre risk after an approval, which the company has agreed to do.
A 66-year-old man in the United States developed Guillain-Barre, and a woman of the same age in Japan was diagnosed with Miller Fisher syndrome, a variant of Guillain-Barre. They developed symptoms respectively seven and eight days after vaccination. The woman has since recovered, and the man’s symptoms resolved since the last update, according to the FDA.
But Alejandra Gurtman, a Pfizer executive, maintained that the company did not identify any safety issues during the trial and that the vaccine was well tolerated.
Gurtman pointed to other potential causes of the Guillain-Barre cases, noting that the man had suffered a heart attack and the woman had an upper respiratory infection. But Dr. Marie Griffin, a member of the FDA’s advisory committee, said the cases raise serious safety concerns.
“It seems to me that one case is a red flag. Two cases are very concerning, and it’s concerning to me that Pfizer doesn’t believe there are any safety issues,” said Griffin, a professor of health policy at Vanderbilt University Medical Center
Dr. Hana El Sahly, who chairs the FDA’s advisory committee, also said the Guillain-Barre cases raise a significant safety concern. El Sahly said the disease has an incidence of about one in 100,000 among people age 60 and older, but in the trial the rate looks more like one in 9,000.
“So this is important if we take it at this level,” El Sahly said, while noting that there is considerable uncertainty about what the actual rate of the disease will be among vaccine recipients. “But nevertheless, it is significant in terms of incidence,” she said.
Dr. David Kaslow, a senior official in the FDA’s vaccine division, said safety monitoring will be “critically important” if Pfizer’s RSV vaccine is approved.
The FDA is currently considering Pfizer’s proposal to study the risk of Guillain-Barre syndrome among Medicare beneficiaries. The FDA has the authority to require such a post-approval study if the agency deems it necessary.
At the time of Tuesday’s meeting, there was not enough data to evaluate the effectiveness of Pfizer’s vaccine against serious illness requiring hospitalization, oxygen support or a mechanical ventilator, according to the FDA. Data were also not available on how long protection from the vaccine would last, according to the agency.
Pfizer also did not have data on how effective the vaccine is for older people with weak immune systems or for those in poor health, according to the FDA.
Griffin, the doctor at Vanderbilt University Medical Center, said she was concerned that the vaccine was being tested in a relatively healthy population where hospitalizations were low, and there was no data on nursing home residents and people in frail health.
Akindele, the FDA official, said real-world evidence after a vaccine rollout could provide answers on how much protection it provides for those in fragile health. The data will then be used to determine whether the FDA needs to make any adjustments to how the shot is used, she said.
Pfizer is conducting its clinical trial over two RSV seasons with more than 34,000 people enrolled. Available data on efficacy and safety are from the first season.
Asked what would happen if the data from the second season is not as strong after an approval, Akindele said the FDA would reconsider the shot and meet with the committee again to decide how to proceed.
Pfizer estimates that if 50% of people age 60 and older get the shot, the vaccine could prevent more than 5,000 deaths, 68,000 hospitalizations, 51,000 emergency room visits and more than 422,000 outpatient visits.