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.

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.

Barré for every million doses given.

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

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.

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.

On Tuesday, January 7, the FDA announced it would now be requiring GSK and Pfizer’s RSV vaccines to hold warnings of a risk of Guillain-Barré syndrome (GBS). This is after post market analysis by the American regulator.

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.

He also articulated a very specific doctrine about the role of an FDA commissioner, one that is limited in its power and leaves many controversial decisions to career government officials. Califf said he would not directly comment on any individual,