This 1981 photo provided by the Centers for Disease Control and Prevention (CDC) shows an electron micrograph of Respiratory Syncytial Virus, also generally known as RSV.
CDC via AP
The Food and Drug Administration sees a possible risk of Guillain-Barre syndrome with Pfizer‘s RSV vaccine for older adults and has asked the corporate to conduct a security study if the shot is approved this spring, based on agency briefing documents published Friday.
Two people of their 60s who received Pfizer’s shot were diagnosed with Guillain-Barre syndrome, out of about 20,000 vaccine recipients within the phase three trial, based on the FDA document. There have been no cases within the trial’s placebo group, the individuals who didn’t receive the shot.
Guillain-Barre syndrome, or inflammatory neuropathy, is a rare disorder by which the body’s immune system mistakenly attacks the nerves. Symptoms range from temporary weakness to paralysis, based on the National Institutes of Health. Most individuals get well, even from severe cases.
Pfizer, in its briefing document, said the cases produce other possible explanations. Nevertheless it said it’ll conduct a security study to further assess Guillain-Barre syndrome after a possible approval. The corporate said it didn’t discover any safety concerns in the course of the trial and the vaccine was well tolerated.
There was also a possible case of Guillain-Barre syndrome in GSK‘s RSV vaccine trials, but the corporate said there was insufficient evidence to verify a diagnosis. GSK has listed Guillain-Barre as a crucial potential risk in its safety surveillance plan, based on the FDA. The agency said it’ll review the plan and make recommendations as needed.
The FDA published the briefing documents ahead of its advisory committee meetings next week. The advisors will vote Tuesday on whether Pfizer’s efficacy and safety data supports an FDA approval. They can even vote Wednesday on GSK’s RSV vaccine for older adults.
No approved RSV vaccine exists. The virus causes anywhere from 6,000 to 10,000 deaths a 12 months amongst seniors, though mortality varies from season to season.
Pfizer’s vaccine was 85% effective at stopping lower respiratory tract illness and GSK’s shot was 83% effective, based on an FDA review of the businesses’ data.
The Guillain-Barre cases
In Pfizer’s trial, a 66-year-old man within the U.S. with a history of hypertension developed Guillain-Barre symptoms seven days after vaccination. The person had a heart attack before the symptoms began, was hospitalized and underwent an angioplasty. The FDA doesn’t view the guts attack as related to the RSV vaccine.
The person developed lower back pain eight days after vaccination after which experienced weakness in his lower extremities on the 14th day. He was hospitalized again after suffering a fall and was subsequently diagnosed with Guillain-Barre Syndrome. His symptoms began improving after treatment and were resolving six months after onset, based on the FDA.
In a second case, a 66-year-old woman in Japan with a history of type 2 diabetes developed a severe case of Miller Fisher syndrome, which is a variant of Guillain-Barre. She experienced fatigue nine days after vaccination, a sore throat the subsequent day and poor muscle control on the tenth day. She was hospitalized 19 days after vaccination, but her symptoms resolved completely in three months.
The FDA said it agrees with investigators that the cases were possibly related to Pfizer’s vaccines. But Pfizer, in its briefing document, said there other possible explanations. The corporate pointed to the person’s heart attack and said the girl had symptoms of an upper respiratory infection.
However the FDA said that given the incidence of Guillain-Barre syndrome in the final population is about 3 cases per 100,000 people annually, Pfizer should view the incidents as a crucial potential risk in its safety surveillance.
“Given the temporal association and biological plausibility, FDA agrees with the assessments of the investigators that these events were possibly related to review vaccine,” the agency said.
Within the case of GSK, a 78-year-old woman in Japan developed lower limb weakness nine days after receiving the primary dose of the RSV vaccine, based on an FDA briefing document. She was participating in an open-label study with no placebo arm for comparison.
The girl had difficulty walking the next day and developed upper limb and respiratory muscle weakness over the subsequent three days. She was hospitalized and treated for Guillain-Barre syndrome. The FDA and the study investigator consider the case to be related to the vaccine.
But GSK, in its briefing document, said a Guillain-Barre diagnosis was not confirmed because of the absence of exam results and since there was no information on whether alternative causes were investigated. The patient’s case was considered resolved after six months, the corporate said.
CDC advisors grapple with risks, advantages
The Centers for Disease Control and Prevention’s committee of independent vaccine advisors grappled with the three cases of Guillain-Barre syndrome during a gathering open to the general public Thursday. Dr. Michael Melgar, a CDC official, told the committee that it’s difficult to find out whether the cases represent an actual safety concern linked to the shots, or in the event that they are random events.
“Resulting from the small variety of events, measures of relative and absolute risk weren’t calculated,” Melgar told the committee members.
But a workgroup of physicians and health officials who reviewed the available data agreed that safety monitoring will probably be critical if the vaccines are approved by the FDA, Melgar said.
A majority of the workgroup felt that the potential advantages of the vaccines would outweigh possible risks for people ages 65 and older, Melgar said. A minority thought that the risk-benefit balance was uncertain due partly to the Guillain-Barre cases.
Although Pfizer and GSK have asked the FDA to approve their respective vaccines for people ages 60 and older, the CDC workgroup generally favored a suggestion for seniors ages 65 and older. The CDC advisory committee didn’t vote on any recommendations for the RSV vaccines this week.
Dr. Sarah Long, a member of the workgroup, said the cases gave her pause since the incidence of Guillain-Barre syndrome increases with age, which suggests seniors might be at higher risk if a link is found to the vaccine sooner or later.
Dr. Grace Lee, the CDC advisory committee chair, said more data is required because respiratory viral illnesses also cause Guillain-Barre syndrome. It’s possible that the vaccines could prevent more cases of Guillain-Barre syndrome by protecting against sickness from RSV.
“You might be stopping more, and we do not know obviously what the speed is, but I just think that balance goes to be really helpful, at the least to me to have the ability to know the best way to think through the benefit-risk balance,” said Lee, associate chief medical officer at Stanford Kid’s Health. “Then I can understand whether or not the 60-year-olds or the 65-year-olds is sensible.”
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