Countries Are Halting the AstraZeneca Vaccine Due to Blood Clot Worries

Denmark suspended the use of AstraZeneca's COVID-19 vaccine for two weeks following reports that some people who received it developed substantial blood clots — possibly killing one person — according to Danish authorities on Thursday.

Soon after, Norway also stopped administering the AstraZeneca vaccine on Thursday. "This is a cautionary decision," said Director Geir Bukholm of Infection Prevention and Control of the Norwegian Institute of Public Health (FHI) during a news conference, according to an Al Jazeera report.

Link between the AstraZeneca vaccine and blood clots is unclear

Danish officials said this action was in response "to reports of possible serious side effects, both from Denmark and other European countries," according to a report from CNBC.

"Against this background, the European Medicines Agency has launched an investigation into the AstraZeneca vaccine. One report relates to a death in Denmark. At present, it cannot be concluded whether there is a link between the vaccine and the blood clots," said a Danish health authority in a statement.

However, the European Union member didn't state precisely how many blood clots had occurred.

This comes on the heels of another similar investigation in Austria by authorities on the death of a person and the illness of another after receiving the AstraZeneca vaccine.

AstraZeneca claims its vaccine underwent 'strong and rigorous' quality control

Notably, Norway's FHI didn't comment on how long this suspension will last. "We ... await information to see if there is a link between the vaccination and this case with a blood clot," said Bukholm, during the conference.

Italy also suspended the rollout of a batch of AstraZeneca's COVID-19 vaccine — since it was different than the one used in Austria. Meanwhile, the pharmaceutical company emphasized in a written statement to Reuters that its vaccine's safety was studied extensively during human trials, with peer-reviewed data affirming the "well-tolerated" reaction to the vaccine.

Earlier this week, AstraZeneca also said its vaccine underwent severe and rigorous quality control, and that there were "no confirmed serious adverse events associated with the vaccine," according to the Reuters report. The drugmaker also claimed it was maintaining talks with Austrian authorities, and fully supports the country's investigation.

On Wednesday, the European Medicines Agency (EMA) — the drug regulating agency of the E.U. — said no evidence yet existed linking AstraZeneca to the two cases under investigation in Austria.

COVID-19 vaccine suspensions are still only precautionary

The EMA also said several blood clots in people who had received the AstraZeneca vaccine is no higher than the rate also seen in the broader population — wherein 22 cases of thromboembrolic events (blood clots) were reported among the three million who as of March 9 had received the vaccine.

As of writing, 136,090 of roughly 5.8 million people in Denmark have received the shot with AstraZeneca's vaccine. The country also uses Moderna and Pfizer/BioNTech's vaccines. Four other countries — including Latvia, Lithuania, Luxembourg, and Estonia — have halted AstraZeneca's vaccine rollout while the investigation goes on, according to the EMA.

Generally, officials have said these actions remain strictly precautionary — since solid links have yet to be proven between the AstraZeneca vaccine, blood clots, and death. And, although officials in Europe investigate for possible issues, there are still two more vaccines in circulation.

This was a breaking story and was regularly updated as new information became available.