Denmark has ceased giving the Oxford-AstraZeneca Covid-19 vaccine amid concerns about rare cases of blood clots, the first European country to do so fully.
The move is expected to delay the country’s vaccination programme by several weeks.
Drug watchdog the European Medicines Agency last week announced a possible link with clots but said the risk of dying of Covid-19 was much greater.
Several European countries had previously briefly suspended the jab.
Most have now resumed vaccinations with AstraZeneca, but often with limits to older age groups.
On Tuesday, the US, Canada and the European Union paused the Johnson & Johnson vaccine for similar reasons over clotting.
South Africa has also paused its use, despite the Johnson & Johnson being its preferred vaccine because of its effectiveness against the South African variant.
For both AstraZeneca and Johnson & Johnson, the blood clot side effects are extremely rare.
The EU’s vaccine roll-out has been criticised by the World Health Organization (WHO) for being too slow, and there are concerns this latest delay could throw it into further turmoil.
Both vaccines work by a similar method, known as adenoviral vectors.
Danish officials said that all 2.4 million doses of the AstraZeneca vaccine would be withdrawn until further notice.
The Danish health authority said studies had shown a higher than expected frequency of blood clots following doses, affecting about one in 40,000 people.
Director-general Soren Brostrom said it had been a “difficult decision” but Denmark had other vaccines available and the epidemic there was currently under control.
“The upcoming target groups for vaccination are less likely to become severely ill from Covid-19,” he said. “We must weigh this against the fact that we now have a known risk of severe adverse effects from vaccination with AstraZeneca, even if the risk in absolute terms is slight.”
However, the authority said it could not rule out using it again at another time.
Almost one million people in Denmark have been vaccinated, with approximately 150,000 of them receiving the AstraZeneca jab. The Pfizer/BioNTech and Moderna vaccines are also in use.
An official from the US Food and Drug Administration told Reuters it was “plainly obvious” that the cases of blood clots linked to the Johnson & Johnson vaccine were “very similar” to those linked to the AstraZeneca vaccine.
Meanwhile, the Czech deputy prime minister Jan Hamacek said he had instructed the Czech ambassador in Denmark to try to buy the 2.4 million AstraZeneca vaccines doses that the Danes would no longer be using.
Denmark was the first country to postpone the use of the AstraZeneca vaccine in March. It was followed by numerous other European countries.