Blood sample for Respiratory Syncytial Virus (RSV) test
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The Food and Drug Administration’s independent advisors on Tuesday recommended the world’s first RSV vaccine, a shot of Pfizer for adults 60 years and older, despite safety concerns after two study participants developed a rare neurological disorder.
A majority of FDA committee members supported the vaccine but wrestled separate votes on whether the safety and efficacy data were sufficient to support agency approval. The FDA’s decision is expected to be made 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 receive FDA approval.
In Tuesday’s first vote, seven members of the FDA committee said the safety data was sufficient for approval, while four said it was not, and one member abstained.
The vote followed concerns at the FDA and among advisory committee members about two cases of Guillain-Barré syndrome in about 20,000 vaccine recipients. Guillain-Barre is a rare neurological disorder in which the body’s immune system mistakenly attacks nerves.
Symptoms can range from brief weakness to paralysis. Most patients, even those with severe cases, recover.
On the second vote, seven committee members said the data on the vaccine’s effectiveness was adequate, while four said it was not, and one member abstained.
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According to an FDA review of Pfizer’s data, the syringe protected about 86% against lower respiratory disease with three or more symptoms and 66.7% against the same disease with two or more symptoms. Symptoms included wheezing, shortness of breath, rapid and shallow breathing, and 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 70 and older are more susceptible.
According to three seasons of CDC data, 19% of adults of all ages hospitalized with RSV require critical care and 4% die. Mortality is highest among the elderly.
Pfizer’s vaccine contains both RSV strains that circulate simultaneously in the fall and winter. The injection is given as a single dose of 120 micrograms.
The Guillain Barre Falls
The FDA considers the two Guillain-Barre cases during the study to be potentially vaccine-related, said Dr. Nadine Peart Akindele, an official at the agency. The FDA has asked Pfizer to develop a safety study to monitor post-approval Guillain-Barre risks, to which the company has agreed.
A 66-year-old man in the United States was diagnosed with Guillain-Barre, and a woman of the same age in Japan was diagnosed with Miller-Fischer syndrome, a variant of Guillain-Barre. They developed symptoms seven and eight days after vaccination, respectively. The woman has since recovered and the man’s symptoms have disappeared since the last update, according to the FDA.
However, Alejandra Gurtman, a Pfizer executive, claimed that the company did not identify any safety concerns during the study and that the vaccine was well tolerated.
Gurtman pointed to other possible 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 Advisory Committee, said the cases raise serious safety concerns.
“It seems to me that a case is a red flag. Two cases are of great concern and I am concerned that Pfizer does not believe there are safety concerns,” said Griffin, professor of public health policy at Vanderbilt University Medical Center
The FDA says safety monitoring is critical
dr FDA Advisory Committee Chair Hana El Sahly also said the Guillain-Barre cases raise significant safety concerns. El Sahly said the disease has an incidence of about 1 in 100,000 in people aged 60 and over, but in the study the rate looks more like 1 in 9,000.
“So that’s of great importance when we look at it at that level,” El Sahly said, while noting that there is significant uncertainty about what the actual rate of the disease among vaccine recipients would be. “But nonetheless, it’s significant in terms of incidence,” she said.
dr David Kaslow, a senior official in the FDA’s Vaccine Division, said safety monitoring will be “vital” if Pfizer’s RSV vaccine is approved.
The FDA is currently reviewing Pfizer’s proposal to study the risk of Guillain-Barré syndrome in Medicare beneficiaries. The FDA has the authority to request such a post-approval study if the agency deems it necessary.
dr Jay Portnoy, a member of the FDA committee, said he had concluded that the safety data was adequate given that Guillain-Barre syndrome was rare and there were otherwise adverse events in the study in people who received the vaccine and occurred at about the same rate in those who did not receive it.
Adam Berger, an official with the National Institutes of Health, said he was concerned about the Guillain-Barre cases but said a larger study population was needed to determine if there was an actual link to the gunshot. The post-approval study planned by the FDA and Pfizer could help answer that question, he said.
“I felt I could vote yes at this point, with a strong bias towards the actual requirements of this post-market surveillance study,” said Berger, who is also a member of the FDA committee.
Incomplete efficacy data
At the time of Tuesday’s meeting, there weren’t enough data to evaluate the effectiveness of Pfizer’s vaccine against serious illnesses that require hospitalization, oxygen support, or a mechanical ventilator, according to the FDA. According to the authority, there was also no data on how long the protection provided by the vaccine would last.
Pfizer also had no data on how effective the vaccine is for older people with weak immune systems or for those with frail health, according to the FDA, according to the FDA.
Griffin, the doctor at Vanderbilt University Medical Center, said she was concerned the vaccine was being tested on a relatively healthy population where hospital admissions were low and that there was no data on nursing home residents and those with frail health.
Akindele, the FDA official, said real-world evidence once a vaccine is released could answer how much protection it offers for those in frail health. The data would then be used to determine if the FDA needs to make adjustments to how the shot is used, she said.
Pfizer is conducting its clinical study over two RSV seasons with more than 34,000 enrolled individuals. The available efficacy and safety data are from the first season.
When asked what would happen if the second-season data isn’t as strong following an approval, Akindele said the FDA will reevaluate the shot and meet again with the committee to determine how to proceed.
Pfizer estimates that if 50% of people age 60 and older get the vaccine, the vaccine could prevent more than 5,000 deaths, 68,000 hospital admissions, 51,000 emergency room visits and more than 422,000 outpatient visits.