This 1981 photo provided by the Centers for Disease Control and Prevention (CDC) shows an electron micrograph of respiratory syncytial virus, also referred to as RSV.
CDC via AP
The Food and Drug Administration sees a possible risk of Guillain-Barre syndrome PfizerRSV vaccine for the elderly and asked the company to conduct a safety study if the vaccine is approved this spring, based on agency briefings published on Friday.
Two people of their 60s who received the Pfizer injection were diagnosed with Guillain-Barre syndrome, out of the roughly 20,000 people vaccinated in the third phase of the study, based on FDA document. There have been no cases in the placebo group of the study, individuals who didn’t receive an injection.
Guillain-Barre syndrome, or inflammatory neuropathy, is a rare disorder where the body’s immune system mistakenly attacks nerves. Symptoms range from transient weakness to paralysis, based on the National Institutes of Health. Most individuals get better, even after severe cases.
Pfizer, in your information document, said the cases produce other possible explanations. However it said it might conduct a safety study to further evaluate the Guillain-Barre syndrome after potential approval. The company said it had not identified any issues of safety during the trial and the vaccine was well tolerated.
A case of Guillain-Barre syndrome was also possible GSKtrials of an RSV vaccine, but the company said there was not enough evidence to verify the diagnosis. In keeping with the FDA, GSK has listed Guillain-Barre as a very important potential risk in its safety oversight plan. The agency said it might review the plan and make recommendations if obligatory.
The FDA released briefing papers ahead of advisory committee meetings next week. Advisors will vote on Tuesday whether Pfizer’s efficacy and safety data supports FDA approval. They may also vote on GSK’s RSV vaccine for the elderly on Wednesday.
There is no approved vaccine against RSV. The virus causes 6,000 to 10,000 deaths a yr amongst seniors, although the mortality rate varies from season to season.
Pfizer’s vaccine was 85% effective in stopping lower respiratory tract disease, and GSK’s vaccine was 83% effective, based on an FDA review of data.
Guillain-Barre affairs
In a Pfizer study, a 66-year-old U.S. man with a history of hypertension developed Guillain-Barre symptoms seven days after vaccination. The man had a heart attack before symptoms developed, was hospitalized and underwent angioplasty. The FDA doesn’t consider heart attack related to the RSV vaccine.
The man developed lower back pain eight days after vaccination and developed lower limb weakness on day 14. He was hospitalized again after a fall and was subsequently diagnosed with Guillain-Barre syndrome. His symptoms began to enhance with treatment and subsided six months after onset, based on the FDA.
In the second case, a 66-year-old Japanese woman with a history of type 2 diabetes developed a severe case of Miller Fisher syndrome, which is a variant of Guillain-Barre. Nine days after vaccination, she had fatigue, a sore throat the next day, and poor muscle control on the tenth day. She was hospitalized 19 days after vaccination, but her symptoms resolved completely inside three months.
The FDA said it agreed with the researchers that the cases were likely related to Pfizer’s vaccines. But Pfizer offered other possible explanations in its briefing paper. The company pointed to the man’s heart attack and said the woman had symptoms of an upper respiratory infection.
But the FDA said that given the prevalence of Guillain-Barre syndrome in the general population of about 3 cases per 100,000 people per yr, Pfizer should view these incidents as a very important potential safety oversight risk.
“Based on the temporal relationship and biological probability, the FDA agrees with the investigators’ assessments that these events were likely related to the study vaccine,” the agency said.
In the case of GSK, a 78-year-old woman in Japan developed lower limb weakness nine days after receiving her first dose of the RSV vaccine, based on an FDA briefing paper. She participated in an open-label study without a placebo arm for comparison.
The woman had difficulty walking the next day and developed weakness in her upper limbs and respiratory muscles over the next three days. She was hospitalized and treated for Guillain-Barre syndrome. The FDA and the researcher consider the case is related to the vaccine.
But GSK in its briefing paper said the Guillain-Barre diagnosis was not confirmed resulting from lack of test results and since there was no information whether alternative causes had been investigated. The patient’s case was considered resolved after six months, the company said.
CDC advisors grapple with risks and rewards
The Centers for Disease Control and Prevention’s Committee of Independent Vaccine Advisers handled three cases of Guillain-Barre Syndrome during a meeting open to the public on Thursday. Dr. Michael Melgar, a CDC official, told the commission that it is difficult to find out whether these incidents are an actual safety issue related to the shots, or in the event that they are random events.
“As a consequence of the small number of events, measures of relative and absolute risk haven’t been calculated,” Melgar told committee members.
But working group of doctors and health officials which reviewed the available data, agreed that safety monitoring can be critical if the vaccines were approved by the FDA, Melgar said.
Most of the working group believed that the potential advantages of the vaccines would outweigh the possible risks for those 65 and older, Melgar said. A minority felt that the benefit-risk balance was uncertain, due partly to the Guillain-Barre cases.
Although Pfizer and GSK each approached the FDA for approval of their respective vaccines for people 60 and older, the CDC working group generally favored the advice for seniors 65 and older. The CDC’s advisory committee didn’t vote on any RSV vaccine recommendations this week.
Dr Sarah Long, a member of the working group, said these cases had stopped her because the incidence of Guillain-Barre syndrome increases with age, meaning seniors could also be at higher risk if found sooner or later relationship with the vaccine.
Dr. Grace Lee, chair of the CDC’s advisory committee, said more data is needed because viral respiratory diseases also cause Guillain-Barre syndrome. It is possible that vaccines could prevent more cases of Guillain-Barre syndrome by protecting against RSV disease.
“You possibly can prevent more, and we do not know obviously what’s at stake, but I just think balance is going to be really helpful, a minimum of for me, to have the option to know easy methods to rethink the balance’s benefit-risk ratio,” said Lee, associate medical director at Stanford Kid’s Health. “Then I can understand whether 60-year-olds or 65-year-olds make sense.”
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