FDA Adds Warning of Rare Reaction Possibly Linked to Johnson & Johnson COVID-19 Vaccine

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

The government said there have been reports of 100 people who got the shot developing an immune system disorder that can cause muscle weakness and occasionally paralysis. The reports represent a tiny fraction of the nearly 13 million Americans who have received the one-dose vaccine.

The announcement said the vaccines most used in the U.S., made by Pfizer and Moderna, show no rise of the disorder.