Dubai, United Arab Emirates (CNN) — After two people received the respiratory syncytial virus (RSV) vaccine during a clinical trial, they were later diagnosed with Guillain-Barre syndrome. The US Food and Drug Administration has asked Pfizer to conduct a safety study if the dose is approved, according to agency documents published Friday.
The two cases were confirmed in two adults in their 60s who were among 20,000 recipients of the vaccine in Pfizer’s Phase 3 clinical trial.
One of them fully recovered from the disease after three months, and the other was improving after six months.
There were no similar cases among people who did not receive the dose.
“Given temporal correlation and biological plausibility, FDA agrees with investigators’ assessments that these events may have been study related,” the FDA says in the documents, which were released before the independent vaccine advisors, the Vaccine and Related Biological Products Advisory Committee, met on Tuesday and Wednesday. The vaccine.. so it is considered [غيلان باريه] significant potential risk.”
The committee is scheduled to discuss and make recommendations regarding respiratory syncytial virus (RSV) vaccines for adults 60 years and over from Pfizer and GlaxoSmithKline, a global British pharmaceutical company.
Guillain-Barre syndrome is a rare neurological disorder in which the body’s immune system attacks nerves, causing muscle weakness and sometimes paralysis.
Although most people recover completely, some cases can be fatal or have permanent effects.
The incidence of Guillain-Barre is between 1.5 and 3 cases per 100,000 adults over the age of 60 in the United States annually, according to the Food and Drug Administration.
“Given the higher rate of Guillain-Barre syndrome observed in the Phase III study, FDA will recommend enhanced post-marketing and surveillance study for further evaluation of Guillain-Barre syndrome and other immunomediated demyelinating conditions with post-marketing use,” the FDA reported.
In a briefing document for next week’s meetings, Pfizer explains that the cases have other possible explanations and that the vaccine is “well tolerated and safe, with a favorable risk-benefit ratio.”
The company says it will conduct a safety study on Guillain-Barre syndrome if the RSV vaccine is approved.
Respiratory syncytial virus is a highly contagious virus that causes a flu-like illness in people of all ages, with severity increasing with age.
According to the US Centers for Disease Control and Control, RSV is responsible for an estimated 177,000 hospitalizations and 14,000 deaths annually among adults 65 and older.
There are no approved vaccines for respiratory syncytial virus (RSV) for children or adults.
The Pfizer vaccine was 66.7% effective in preventing moderate lower respiratory disease with two or more symptoms, and 85.7% effective in preventing severe disease, according to FDA documents.
As for the GlaxoSmithKline vaccine for the elderly, it was 83.5% effective in preventing severe lower respiratory diseases.
Similarly, the company reported a possible case of Guillain-Barre syndrome among vaccine recipients, but stated that there was insufficient evidence to confirm the diagnosis.
The Food and Drug Administration considers the condition to be linked to the vaccine and said it will review GlaxoSmithKline’s safety plan.
The vaccine data was discussed Thursday during a meeting of the CDC’s Immunization Practices Advisory Committee.
The working group concluded that the vaccines “demonstrated significant efficacy against lower respiratory illnesses caused by respiratory syncytial virus in the elderly” but that “post-licensing monitoring of both safety and vaccine efficacy will be critical” if the vaccines are approved by the FDA.