J&J vaccine restricted over blood clot risk

The US Food and Drug Administration, or FDA, on Thursday put a limit on Johnson & Johnson's COVID-19 vaccine due to a rare but dangerous risk of blood clots.

The agency is limiting its use to people aged 18 and older who can't receive a different vaccine or specifically request Johnson & Johnson's because they wouldn't otherwise get vaccinated.

The FDA said in a statement that the change is being made because of the blood-clotting condition called thrombosis with thrombocytopenia syndrome that can occur after the vaccine is administered. While the blood clots seen with the US drugmaker's shot are rare, the FDA said they are still occurring.

The federal health agency said that it decided to restrict the vaccine after taking another look at data on the risk of life-threatening blood clots within two weeks of vaccination.

It said federal scientists identified 60 cases, including nine that were fatal, as of mid-March. That amounts to one blood clot case per 3.23 million Johnson & Johnson shots administered.

A spokesman for the New Jersey-based drug producer said in a statement: "Data continue to support a favorable benefit-risk profile for the Johnson & Johnson COVID-19 vaccine in adults, when compared with no vaccine."

As of Thursday, more than 18.7 million doses of the company's vaccine have been administered in the United States, according to the Centers for Disease Control and Prevention, or CDC. Of those who are considered fully vaccinated, 7.7 percent got the vaccine.

Pfizer and Moderna have provided the vast majority of COVID-19 vaccines in the United States. More than 200 million people in the US have been fully vaccinated with the two.

In December, the CDC recommended prioritizing the Moderna and Pfizer shots over Johnson &Johnson's because of the latter's safety issues.

Pfizer and Moderna require two doses, but Johnson & Johnson's vaccine is a single dose; follow-up studies have consistently shown lower effectiveness for it.

Despite the restriction, FDA vaccine chief Peter Marks said the company's vaccine "still has a role in the current pandemic response in the United States and across the global community".

COVID-19 causes deadly blood clots, too. But the vaccine-linked kind is different, believed to form because of a rogue immune reaction to the Johnson & Johnson and AstraZeneca vaccines because of how they are made.