10:48 AM EST, 01/08/2025 (MT Newswires) -- GSK (GSK) and Pfizer's ( PFE ) respiratory syncytial virus vaccines will carry warnings of increased risk of Guillain-Barre Syndrome, the US Food and Drug Administration said Tuesday on its website.

Results from a post-marketing observational study suggested an increased risk of Guillain-Barre Syndrome (GBS) during the 42 days after vaccination with Pfizer's ( PFE ) Abrysvo and GSK's Arexvy, the FDA said.

GBS is a rare disorder in which the body's immune system damages nerve cells, causing muscle weakness and sometimes paralysis.

The FDA said it has "determined that the overall body of evidence suggests increased risks of GBS with Abrysvo and Arexvy, but that available evidence is insufficient to establish a causal relationship."

"FDA has required and approved safety labeling changes to the Prescribing Information for Abrysvo and Arexvy," the regulator said.

"FDA has further determined that the benefits of vaccination with Abrysvo and Arexvy continue to outweigh their risks," it added.

GSK and Pfizer ( PFE ) didn't immediately respond to requests for comment by MT Newswires.

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