Denmark is suspending the use of the Oxford-AstraZeneca vaccine for two weeks as it investigates reports of some patients developing blood clots after being inoculated, days after several other EU countries suspended use of a specific batch of the vaccine.
Danish Health Minister Magnus Heunicke said Thursday authorities were looking into "signs of a possible serious side effect in the form of fatal blood clots," though he made clear it was a "precautionary measure," saying it was not possible yet to conclude whether the clots were linked to the vaccine.
"We act early, it needs to be thoroughly investigated," he said in a tweet.
The Danish Health Authority also confirmed the suspension in a statement, saying its investigation would include looking into one death in Denmark.
"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. 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," Søren Brostrøm, director of the National Board of Health, said in the statement.
"It is important to emphasize that we have not opted out of the AstraZeneca vaccine, but that we are putting it on hold. There is good evidence that the vaccine is both safe and effective. 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. "
The Danish Medicines Agency said it was working with the European Medicines Agency (EMA) and the other EU pharmaceutical authorities to investigate several reports of blood clotting.
Earlier this week, Austria suspended the use of one specific batch of the AstraZeneca vaccine -- batch ABV5300 -- after "a person was diagnosed with multiple thrombosis," according to EMA.
As of Tuesday, Estonia, Lithuania, Luxembourg and Latvia had also suspended use of batch ABV5300.
It has not been specified if the Danish death was connected to this batch.
EMA said Wednesday there was "currently no indication that vaccination has caused these conditions, which are not listed as side effects with this vaccine."
"Batch ABV5300 was delivered to 17 EU countries and comprises 1 million doses of the vaccine. Some EU countries have also subsequently suspended this batch as a precautionary measure, while a full investigation is ongoing. Although a quality defect is considered unlikely at this stage, the batch quality is being investigated," EMA said in a statement.
The investigation is the latest trouble in Europe for British-Swedish drugmaker AstraZeneca, which has come under pressure to produce more vaccines after it fell tens of millions of doses short in deliveries to the European Union.
Italy banned the export of 250,000 doses of the shot to Australian last week in an effort to protect its national supplies. France said it would also consider banning exports, as concerns of vaccine nationalism rise.
The company has also faced resistance in the bloc, where regulatory bodies in member countries have been slow or hesitated to recommend the vaccine in people over the age of 65, citing a lack of data.
Regulatory bodies in several countries, including Germany and France, have since changed recommendations to include over 65s as real-world data has since shown that the AstraZeneca vaccine is highly effective at preventing hospitalization in older populations. France limits the shot to people under the age of 74.
Anecdotal reports suggest people in some EU countries, however, are still choosing not to take the AstraZeneca vaccine.
CNN's Angela Dewan contributed to this report.