The U.S. Food and Drug Administration (FDA) ordered two respiratory syncytial virus (RSV) vaccine manufacturers to include a potentially paralytic side effect warning related to nerve damage on product labels.

The manufacturers, GSK and Pfizer, manufacturing Arexvy and Abrysvo vaccines respectively, must now include a warning stating a risk of Guillain-Barre syndrome (GBS) following vaccination, according to a Jan. 7 statement from the agency.
GBS is a rare disorder in which the immune system ends up damaging nerve cells, which leads to weakness in the muscles and potential near-total paralysis, depending on severity.