Europe's medicines regulator said that blood clots should be listed as a “very rare” side effect of Johnson & Johnson's coronavirus vaccine, but that the benefits of the shot still outweighed the risks, AFP reported.

After reviewing isolated cases of clotting among people who received the vaccine, EMA's safety committee said it found a “possible link” to the jab.

The regulator said its safety committee “concluded that a warning about unusual blood clots with low blood platelets should be added to the product information” for the J&J shot.

“This is a very rare effect,” EMA chief Emer Cooke told reporters. “But it also makes it very important for doctors and patients to be aware of the signs so that they can spot any concerns.”