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Newly introduced vaccines against the respiratory syncytial virus (RSV) can slightly increase the risk of developing a rare nervous system disorder called Guillain-Barré syndrome, federal health officials said this week.
The findings presented at a CDC advisory committee meeting on Thursday indicated more than 20 GBS cases out of 9.5M of those who received the vaccines developed by GSK (NYSE:GSK) and Pfizer (NYSE:PFE) late last year.
According to the CDC, GBS is commonly found in older people in the U.S., where an estimated 3,000–6,000 cases are recorded each year.
The condition, linked to viral infections, is also associated with other vaccines, including those against flu and shingles.
Out of every 1M people who receive a vaccine, there can be about two cases of GBS, a rare autoimmune condition that can lead to muscle weakness and paralysis.
The CDC endorsed Arexvy and Abrysvo RSV shots developed by GSK (GSK) and Pfizer (PFE) for certain adults aged 60 and older in June.
Before the vaccines went on sale, the officials were aware of the risk of GBS, and the agency had put in place surveillance systems to track potential issues.
Data from the CDC indicated that the GBS incidence post-Abrysvo vaccination was about five times higher than expected. Meanwhile, GBS rates after Arexvy were not statistically significant.
However, the officials said it was too early to come to a definitive conclusion because of the preliminary nature of the review.
“At this point, due to the uncertainties and limitations, these early data cannot establish if there is an increased risk for G.B.S. after vaccination in this age group,” Thomas Shimabukuro, director of the CDC’s Immunization Safety Office, said.
Ongoing surveillance “will be better able to determine if an increased risk for G.B.S. after R.S.V. vaccination is present, and if so, the magnitude of the risk,” he added.