Denmark, Iceland and Norway have suspended use of the AstraZeneca COVID-19 vaccine as a precaution amid reports of blood clotting in some people who have received it.
The Danish health authority said that there was a reported death in the country but that "at present, it cannot be concluded whether there is a link between the vaccine and the blood clots."
Use of the vaccine will be suspended until further notice, the health authority said on Thursday, but the decision will be reviewed in two weeks' time.
Shortly after the Danish announcement, Iceland followed suit. Hours later, the Norwegian health authority also said they too would suspend vaccinations after the report from Denmark.
France and the UK have however ruled out the following suit for now, stressing the suspension in other countries "is a precautionary measure".
Austria suspends vaccine batch
It comes after Austria suspended a batch of the vaccines following the death of a woman due to multiple blood clots and the hospitalisation of another person with a blockage in the arteries of the lungs.
The vaccine batch, which comprised of one million doses, was subsequently suspended in four other EU countries as a precaution.
The European Medicines Agency said they were reviewing the incidents as well as all other "conditions related to blood clots" but a preliminary review suggested there was no "specific issue" with the batch.
As of Tuesday, the medicines regulator said, there were 22 cases of blood clotting reported among the three million people vaccinated with the AstraZeneca vaccine in the European Economic Area.
“We are in the middle of the largest and most important vaccination rollout in Danish history. And right now we need all the vaccines we can get. Therefore, putting one of the vaccines on pause is not an easy decision," said Søren Brostrøm, Director General of the Danish Health Authority.
"But precisely because we vaccinate so many, we also need to respond with timely care when there is knowledge of possible serious side effects. We need to clarify this before we can continue to use the vaccine from AstraZeneca."
The change means that people who have received their first dose of the AstraZeneca vaccine in Denmark will have to wait before they receive the second dose, the health authority said.
Frontline health staff aged 65 or over will continue to receive vaccination appointments with one of the other two vaccines, they specified.
The authority said they are not opting out of the AstraZeneca vaccine but just putting it on hold.
"There is good evidence that the vaccine is both safe and effective," Brostrøm said.
"But both we and the Danish Medicines Agency have to react to reports of possible serious side effects, both from Denmark and other European countries. It shows that the monitoring system works."
A senior official at the National Institute of Public Health, Geir Bukholm, told reporters on Thursday afternoon: "We are taking a break in Norway from vaccination with AstraZeneca."
"We are waiting for information to see if there is a link between the vaccination and this case of blood clots.
"It is the precautionary principle," Bukholm said, stressing that no link had yet been established between the Anglo-Swedish laboratory's vaccine and the cases of thrombosis, including one fatality, reported in Denmark.
What have other countries said?
In a statement issued in reaction to the Danish announcement, Britain's government said "people should still go and get their COVID-19 vaccine when asked to do so."
"It has not been confirmed that the report of a blood clot, in Denmark, was caused by the COVID-19 Vaccine AstraZeneca," Dr Phil Bryan, Safety Lead at the Medicines and Healthcare products Regulatory Agency, said.
"Blood clots can occur naturally and are not uncommon. More than 11 million doses of the COVID-19 Vaccine AstraZeneca vaccine have now been administered across the UK.
"Reports of blood clots received so far are not greater than the number that would have occurred naturally in the vaccinated population," he added.
France's Health Minister, Olivier Véran, told a press conference in the late afternoon that according to the nation's High Authority for Health "there is no reason to suspend vaccinations with AstraZeneca".
"Out of five million Europeans [vaccinated with AstraZeneca], 30 people have suffered blood clots.
"This does not constitute a statistical excess risk. Out of 5 million unvaccinated Europeans, you would expect 30 of them to have blood clots. What we call the benefit-risk ratio is greater than the risk at this stage, and investigations are ongoing," he told reporters.
The AstraZeneca COVID-19 vaccine has been the focus of much attention and many news headlines in EU countries over the last few months. Earlier this year, before it was approved in the European Union, the company said that they would not be able to deliver promised doses to member states in the first quarter of the year.
The announcement sparked a bitter row with the European Commission, prompting the EU to issue a new export regulation on coronavirus vaccines.
After the vaccine's approval, some countries then said they would not recommend it for older individuals citing a lack of information about individuals over the age of 65 in the trial. However, the European Medicines Agency recommended authorising the vaccine for anyone over the age of 18.