According to agency briefing slides released on Friday, the Food and Drug Administration sees a possible risk of Guillain-Barré syndrome with Pfizer’s RSV vaccination for older individuals and has urged the company to conduct a safety study if the injection is approved this spring. According to the FDA filing, two patients in their 60s who received Pfizer’s injection developed Guillain-Barré syndrome out of approximately 20,000 vaccination trial participants.
In the trial’s placebo group — those who did not receive the injection — there were no cases. Guillain-Barre syndrome, also known as inflammatory neuropathy, is a rare condition in which the immune system mistakenly attacks the nerves. The National Institutes of Health list numerous symptoms, including temporary weakness and eventual paralysis. Even in the worst of circumstances, the majority of people recover.
Pfizer stated in its briefing materials that there may be additional causes for the occurrences. However, it stated that after a prospective approval, a safety study would be conducted to further evaluate Guillain-Barré syndrome. According to the company, the trial revealed no safety concerns and the vaccination was well received.
Additionally, there may have been a case of Guillain-Barré syndrome in GSK’s RSV vaccination studies, but the company argued there was insufficient evidence to make a diagnosis. According to the FDA, GSK’s safety surveillance plan identifies Guillain-Barré syndrome as a significant potential risk. According to the agency, it will evaluate the strategy and make any necessary recommendations.
The FDA made the briefing materials available the week prior to the advisory committee meetings. Tuesday, the advisors will determine whether the FDA should approve Pfizer’s safety and efficacy findings. They will also vote on the GSK RSV vaccination for senior citizens on Wednesday.
There is no authorised RSV vaccine. Depending on the season, the virus is responsible for between 6,000 and 10,000 deaths per year among the elderly. According to an FDA evaluation of the companies’ data, Pfizer’s vaccination was 85 percent effective at preventing diseases of the lower respiratory tract, while GSK’s vaccination was 83 percent effective.
The Guillain-Barre cases
A 66-year-old American man with a history of hypertension showed symptoms of Guillain-Barré syndrome seven days after receiving the vaccine in Pfizer’s experiment. Prior to the onset of symptoms, the man was admitted to the hospital, underwent an angioplasty, and suffered a heart attack. According to the FDA, the RSV vaccine was not a factor in the heart attack.
Eight days after receiving the vaccination, the man began to experience lower back pain, and fourteen days later, he began to experience weakness in his lower extremities. Following his fall, he was required to return to the hospital, where Guillain-Barré Syndrome was diagnosed. According to the FDA, his symptoms improved after treatment and disappeared six months after first appearing.
A 66-year-old Japanese woman with a history of type 2 diabetes later developed a severe case of Miller-Fisher syndrome, a form of Guillain-Barré syndrome. On the ninth day after vaccination, she felt exhausted, the following day she had a sore throat, and on the tenth day she had poor muscle control. Although she was admitted to the hospital 19 days after the vaccination, all of her symptoms had disappeared three months later.
The FDA stated that it agrees with the investigators’ theory that the incidents may be related to Pfizer’s vaccinations. However, Pfizer stated in its briefing document that additional causes may exist. The company highlighted the man’s heart attack while asserting that his wife exhibited symptoms of an upper respiratory infection.
The FDA stated, however, that Pfizer should consider the cases as a significant potential risk in its safety surveillance, given that the incidence of Guillain-Barré syndrome in the general population is approximately 3 cases per 100,000 people annually. Given the temporal correlation and biological plausibility, the FDA concurred with the investigators’ conclusions that these events may have been related to the study vaccine, the agency stated.
According to an FDA briefing paper, a 78-year-old Japanese woman experienced lower limb weakness nine days after receiving the first dose of the RSV vaccine from GSK. She participated in an open-label study with no placebo-receiving control group. The next day, the woman had difficulty walking, and over the next three days, her upper limb and respiratory muscles began to weaken.
She was hospitalised and treated for Guillain-Barré syndrome. The FDA and the study’s investigator consider the incident to be related to the vaccine. However, GSK stated in its briefing document that a Guillain-Barre diagnosis was not established due to the absence of exam findings and information regarding whether alternative causes were considered. Six months later, the business announced that the patient’s case had been closed.
CDC advisors weigh risks and benefits
The committee of independent vaccine advisors for the Centers for Disease Control and Prevention discussed the three cases of Guillain-Barré syndrome during a public meeting on Thursday. Dr. Michael Melgar, a CDC representative, told the committee that it is difficult to determine whether the cases reflect a genuine safety concern related to the vaccinations or whether they are merely coincidental.
Melgar informed the committee that relative and absolute risk measurements were not estimated “due to the small number of incidents.” However, if the FDA approves the vaccinations, safety monitoring would be crucial, according to a group of doctors and health experts who analysed the data.
According to Melgar, the majority of the workgroup believed that the potential benefits of vaccinations would outweigh any potential risks for those aged 65 and older. Due in part to the occurrences of Guillain-Barré, a minority of individuals believed that the risk-benefit ratio was questionable.
Even though Pfizer and GSK have requested that the FDA approve their respective vaccinations for people aged 60 and older, the CDC panel largely supported a proposal for seniors age 65 and older. This week, no recommendations for the RSV vaccination were presented to the CDC advisory committee for a vote.
According to Dr. Sarah Long, a member of the workgroup, the cases give her pause because if there is evidence linking the vaccine to Guillain-Barre syndrome, seniors may be at a greater risk due to the condition’s increasing prevalence with age. According to Dr. Grace Lee, the leader of the CDC advisory committee, additional information is required because respiratory virus diseases can also cause Guillain-Barre syndrome.
Vaccinations may be able to prevent more cases of Guillain-Barre syndrome by protecting against RSV infection. Lee, associate chief medical officer at Stanford Children’s Health, stated, “You may be preventing more, and we don’t know for sure what the rate is, but I believe that understanding the benefit-risk balance will be incredibly beneficial, at least to me.” “After that, I’ll know if the sixty- and sixty-five-year-olds make sense.”
