US FDA adds warning about rare reaction to J&J COVID-19 vaccine

U.S. regulators on Monday added a new warning to Johnson & Johnson’s COVID-19 vaccine about links to a rare and potentially dangerous neurological reaction, but said it’s not entirely clear the shot caused the problem.

The Food and Drug Administration announced the new warning, flagging reports of Guillain-Barre syndrome, an immune system disorder that can causes muscle weakness and occasionally paralysis. Health officials described the side effect as a “small possible risk” for those getting the shot.