Three countries will temporarily stop the rollout of the Johnson and Johnson (J&J) Covid jab, after reports of rare blood clotting.
Six cases were detected in more than 6.8 million doses of the vaccine, the US Food and Drug Administration (FDA) said.
The FDA said it was recommending the temporary pause “out of an abundance of caution”. It confirmed that one patient died from blood clotting complications, and another is in a critical condition.
All six cases were in women aged between 18 and 48, with symptoms appearing six to 13 days after vaccination.
The US has by far the most confirmed cases of Covid-19 – more than 31 million – with more than 562,000 deaths, another world high.
Johnson & Johnson has paused its EU rollout, which started this week.
However deliveries of the vaccine to EU countries started just 24 hours before J&J said it would pause the European rollout.
As it has not been administered in the EU yet, experts there will be looking to the United States to see what their next move is.
It follows similar cases after doses of the AstraZeneca vaccine, which prompted curbs to its use.
South Africa’s Health Minister Zweli Mkhize has announced the suspension of the Johnson & Johnson Covid-19 jab to investigate a possible link with blood clots.
Mkhize said the decision was a “precautionary suspension.”
In a joint statement, the FDA and the Centres for Disease Control and Prevention (CDC) said they were “reviewing data involving six reported US cases of a rare and severe type of blood clot in individuals after receiving the J&J vaccine”.
It said the clotting was called cerebral venous sinus thrombosis (CVST).
The statement said that this type of blood clot needed a different treatment than usual.
The common treatment – an anticoagulant drug called heparin – “may be dangerous”, it said.
Pending a further review, the FDA and CDC recommended “a pause in the use of this vaccine out of an abundance of caution”.
The joint statement said that “people who have received the Johnson & Johnson vaccine who develop severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination should contact their health care provider”.
J&J is a US health care company, but the vaccine was developed mainly by its pharmaceutical branch in Belgium, and is also known as Janssen.
Dr Anthony Fauci, the country’s top Covid adviser, said it was too early to comment on whether it could have its authorisation revoked.
The World Health Organization told Reuters it was monitoring the situation and waiting for reports from the US and European regulators.