The U.S. Food and Drug Administration and the Centers for Disease Control and Prevention issued a joint statement Tuesday, recommending a pause on the use of Johnson and Johnson's Janssen vaccine, after six cases of blood clots were reported six to 13 days after the patients received the single-dose vaccine.
"This morning, the FDA and CDC announced that out of an abundance of caution we're recommending a pause in the use of the Johnson & Johnson Covid-19 vaccine due to reports of six cases of a rare and severe type of blood clot following vaccine administration."
A number of cities and states have already halted its use, although it's not a mandate.
The state of New York has urged people scheduled to receive the Janssen shot to keep their appointments, but they'll receive the Pfizer vaccine instead.
Federal health officials stress that the blood clotting side effects are extremely rare, and the six cases are out of nearly 7 million people who have received the shots.
However, according to the CDC, people who have received the Janssen vaccine in recent weeks should look for any signs of the rare side effect.
These include headaches, severe abdominal pain, leg pain, or shortness of breath, up to three weeks after getting the shot.
Johnson and Johnson says it will delay the rollout of its vaccine in Europe after the U.S. move.
European officials say J&J began delivering its vaccine to the EU on Sunday, and is committed to delivering 55 million doses to the bloc by the end of June, with another 120 million in the third quarter.
The European Medicines Agency said it's not yet clear whether there's a link between the vaccine and the blood clots, but added its safety committee is reviewing the situation.
The WHO says it's monitoring its global database of adverse effects stemming from the vaccine, to see if there have been cases elsewhere.
The agency added it was watching the situation closely, and will wait for the FDA and EMA reports to come out.
Lee Seung-jae, Arirang News.