The FDA will require GSK and Pfizer to include on the label of their respiratory syncytial virus (RSV) vaccines a warning about the risk of developing Guillain-Barré syndrome (GBS), a rare neurological condition that can cause paralysis.

The CDC recommends a single dose of any FDA-approved RSV vaccine for all adults ages 75 years and older, as well as for 60- to 74-year-olds who are at increased risk of severe illness from the virus. A third approved product, Moderna's mRNA vaccine (mResvia), was not included in the safety warning.

As for GBS itself, this neurological ailment can be severe, attacking nerves and warranting hospitalisation for weeks or months. It can influence a variety of nerves from senses to movement, and even heart rhythm, with initial symptoms manifesting typically in the limbs.

Barré syndrome, although it said data don’t prove a causal link and affirmed the shots’ benefit outweighs their risks.

FDA updates safety labels for Pfizer's Abrysvo and GSK's Arexvy RSV vaccines, citing increased Guillain-Barré syndrome risk. Study estimates 7-9 excess GBS cases per million doses.

The FDA is adding a warning about Guillain-Barré syndrome to the respiratory syncytial virus vaccines manufactured by GSK and Pfizer based on data that suggest there may be a link between the shots and the rare disorder.

A post-marketing review by the FDA detected an increased risk of the autoimmune condition in patients inoculated with GSK’s Arexvy and Pfizer’s Abrysvo, prompting the regulator to require adjustments to the vaccines’ labels.

Barré for every million doses given.

GSK and Pfizer's respiratory syncytial virus (RSV) vaccines will carry warnings that they can increase the risk of developing a rare neurological disorder, the U.S. Food Drug Administration said on Tuesday.