New York: US health authorities called for a pause in the use of the Johnson & Johnson Covid-19 vaccine, after reports surfaced of extremely rare blood clotting.
All six cases were in young women aged between 18 and 48, with symptoms showing six to 13 days after vaccination. One of them died and another is in hospital, the New York Times reports.
Johnson & Johnson's jab is the only one-dose vaccine being used so far; it works in a similar way as AstraZeneca's, which is also embroiled in blood clot concerns. Both vaccines use an adenovirus to transport part of the coronavirus into the body.
Incidentally, British vaccine regulators are expected to give the green signal to the pioneering one-shot vaccine this week. The UK has ordered 30million doses of the jab, which would be enough to immunise more than half of the adult population.
The US Food and Drug Administration said it was acting "out of an abundance of caution". It said six cases of severe blood clotting had been detected in more than 6.8 million doses of the vaccine.
In the United States, 300,000 to 600,000 people a year develop blood clots, according to CDC data. But the particular blood clotting disorder that the vaccine recipients developed, known as cerebral venous sinus thrombosis, is extremely rare and needs a different treatment than usual. The common treatment - an anticoagulant drug called heparin - "may be dangerous", the FDA said and added that an alternative was required.
The company's shares were down 3 per cent before the opening bell.
Clinical trials suggest the J&J vaccine offers 100 per cent protection from severe Covid leading to hospitalisation or death, and around 66 per cent protection from mild infection.
