FDA says Guillain-Barré syndrome is a possible risk of Pfizer RSV vaccine

This 1981 photograph provided by the Centers for Disease Control and Prevention (CDC) shows an electron micrograph of the respiratory syncytial virus, also known as RSV.

CDC via hotspot

FDA Sees Possible Risk of Guillain-Barré Syndrome pfizerRSV vaccines for the elderly and asked the company to conduct a safety study if the vaccine is approved this spring, according to agency briefing documents released Friday.

Two people in their 60s who received the Pfizer vaccine were diagnosed with Guillain-Barré syndrome out of approximately 20,000 vaccine recipients in the Phase III trial. according to FDA document. There were no cases in the placebo group, which did not receive the vaccine.

Guillain-Barré syndrome, or inflammatory neuropathy, is a rare condition in which the body’s immune system mistakenly attacks nerves. Symptoms range from short-term weakness to paralysis, according to the National Institutes of Health. Most people recover even in severe cases.

pfizer, in his white paper, said the cases have other possible explanations. But he said he would conduct a safety study to further evaluate Guillain-Barré syndrome after potential approval. The company said it did not identify any safety issues during trials and the vaccine was well tolerated.

There was also a possible case of Guillain-Barré syndrome. GSKtrial of an RSV vaccine, but the company said there was not enough evidence to support the diagnosis. According to the FDA, GSK has listed Guillain-Barre as an important potential risk in its safety oversight plan. The agency said it would review the plan and make recommendations as needed.

The FDA released briefing papers ahead of its advisory committee meetings next week. On Tuesday, consultants will vote on whether Pfizer’s efficacy and safety data support the FDA’s approval. On Wednesday, they will also vote on the GSK RSV vaccine for the elderly.

There is no approved vaccine for RSV. The virus causes between 6,000 and 10,000 deaths per year in the elderly, although mortality varies from season to season.

The Pfizer vaccine was 85% effective in preventing lower respiratory disease, and the GSK vaccine was 83% effective, according to an FDA review of these companies.

In a Pfizer study, a 66-year-old US man with hypertension developed Guillain-Barré symptoms seven days after vaccination. The man had a heart attack before the onset of symptoms, was hospitalized and underwent an angioplasty. The FDA does not treat heart attack as related to the RSV vaccine.

The man developed lower back pain eight days after vaccination, and then on the 14th day developed weakness in the lower extremities. He was hospitalized again after the fall and was subsequently diagnosed with Guillain-Barré syndrome. According to the FDA, his symptoms began to improve after treatment and disappeared six months after the onset of the disease.

In the second case, a 66-year-old woman from Japan with a history of type 2 diabetes developed a severe case of Miller-Fischer syndrome, which is a variant of Guillain-Barré syndrome. She experienced fatigue nine days after vaccination, sore throat the next day, and poor muscle control on day 10. She was admitted to the hospital 19 days after the vaccination, but her symptoms completely disappeared after three months.

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The FDA said it agreed with investigators that the cases may have been linked to Pfizer’s vaccines. But Pfizer, in its white paper, says there are other possible explanations. The company pointed to the man’s heart attack and said the woman had symptoms of an upper respiratory tract infection.

But the FDA said that given that the incidence of Guillain-Barré syndrome in the general population is about 3 cases per 100,000 people per year, Pfizer should consider these incidents as an important potential risk in its safety oversight.

“Given the temporal relationship and biological plausibility, the FDA concurs with the investigators’ assessments that these events may have been related to the study vaccine,” the agency said in a statement.

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, according to an FDA background paper. She participated in an open-label study without a placebo group for comparison.

The next day, the woman had difficulty walking, and over the next three days, she developed weakness in her upper limbs and respiratory muscles. She was hospitalized and treated for Guillain-Barré syndrome. The FDA and the researcher believe the case is related to the vaccine.

But GSK said in its white paper that Guillain-Barré’s diagnosis was not confirmed due to lack of test results and lack of information on whether alternative causes had been investigated. The patient’s case is considered resolved in six months, the company said.

The Centers for Disease Control and Prevention’s Committee of Independent Vaccine Advisers reviewed three cases of Guillain-Barré syndrome during a meeting open to the public on Thursday. Dr. Michael Melgar, a spokesperson for the CDC, told the committee it is difficult to determine whether these cases represent a real vaccine-related safety issue or if they are random events.

“Due to the small number of events, relative and absolute risk metrics were not calculated,” Melgar told committee members.

But working group of doctors and medical workers Melgar said those who reviewed the available evidence agreed that safety monitoring would be critical if vaccines were approved by the FDA.

Most of the task force felt the potential benefits of vaccines outweighed the possible risks for people aged 65 and over, Melgar said. A minority felt that the risk-benefit ratio was uncertain in part because of the Guillain-Barré cases.

While Pfizer and GSK have asked the FDA to approve their respective vaccines for people aged 60 and over, the CDC task force has generally approved the recommendation for seniors aged 65 and over. The CDC advisory committee did not vote on any RSV vaccine recommendations this week.

Dr. Sarah Long, a member of the task force, said the cases made her think because the incidence of Guillain-Barré syndrome increases with age, meaning older people may be at higher risk if an association is found at some point in the vaccine.

Dr. Grace Lee, chair of the CDC advisory committee, said more data is needed because respiratory viral diseases also cause Guillain-Barré syndrome. It is possible that vaccines could prevent more cases of Guillain-Barré syndrome by protecting against RSV.

“Maybe you are preventing more and we don’t know for sure what the speed is, but I just think the balance will be really helpful, at least for me, to understand how to think through the benefit-risk ratio. balance,” said Lee, deputy chief medical officer at Stanford Children’s Health. “Then I can figure out if 60-year-olds or 65-year-olds make sense.”

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