AstraZeneca COVID Vaccine Suspended Over Blood Clot Fears. Should Americans Be Worried?

Some 17 European countries have suspended the use of the AstraZeneca COVID-19 vaccine, amid unconfirmed suspicions that it may have been responsible for causing blood clots in some recipients.

The vaccine, which was created by British-Swedish pharmaceutical company AstraZeneca and the University of Oxford, was approved for use in the U.K. in December and across the 27 member states of the European Union the following month.

However, as shown in the Statista graphic below, countries including Austria, Denmark, Estonia, France, Germany, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Romania, Slovenia, Spain and Sweden have all suspended the AstraZeneca vaccine's use over the past week, after reports that a small number of people had developed blood clots after receiving it.

astrazeneca covid vaccine, statista,
A graphic by Statista shows the countries that have suspended use of the AstraZeneca COVID vaccine. Statista

However, numerous scientific bodies, including the World Health Organization (WHO), European Medicines Agency (EMA), and Medicines and Healthcare products Regulatory Agency (MHRA) have stressed that there is no evidence of a link between the AstraZeneca vaccine and the clotting incidents, also known as "thromboembolic events."

The EMA, which is investigating the reports, said that as of March 10 there had been just 30 reports of thromboembolic events from nearly 5 million people who had received the AstraZeneca vaccine in the European Economic Area.

"Many thousands of people develop blood clots annually in the EU for different reasons. The number of thromboembolic events overall in vaccinated people seems not to be higher than that seen in the general population," the EMA has said.

It added: "While its investigation is ongoing, EMA currently remains of the view that the benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalization and death, outweigh the risks of side effects."

The WHO, which is also investigating, has urged countries not to suspend use of the vaccine.

"As of today, there is no evidence that the incidents are caused by the vaccine and it is important that vaccination campaigns continue so that we can save lives and stem severe disease from the virus," WHO spokesperson Christian Lindmeier said on Monday.

"We are closely reviewing reports but the evidence available does not suggest the vaccine is the cause," said Phil Bryan, vaccines safety lead at the MHRA.

"Blood clots can occur naturally and are not uncommon. More than 11 million doses of the COVID-19 Vaccine AstraZeneca have now been administered across the UK, and the number of blood clots reported after having the vaccine is not greater than the number that would have occurred naturally in the vaccinated population."

AstraZeneca has also defended its vaccine, saying that 15 cases of deep vein thrombosis and 22 cases of pulmonary embolism had been reported to the company from around 17 million vaccinations as of March 8, which is "much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed COVID-19 vaccines."

The company has promised to publish its latest monthly safety report this week.

Some of the countries that have suspended the use of the AstraZeneca vaccine say the measure is temporary and they will continue to use it when the suspected link is disproved, while other countries have stopped using individual batches of the vaccine.

Though there is no evidence that the AstraZeneca vaccine is responsible for the thromboembolic events that some people have experienced, what complicates matters is that some people have experienced short-term side effects after receiving a COVID-19 shot, with soreness at the site of injection, headaches, fever and fatigue being some of the most common of these.

Possible long-term side effects may only emerge long after millions of people have been immunized.

The AstraZeneca vaccine has not yet been approved for use in the U.S., but an ongoing Phase III clinical trial assessing the vaccine is expected to be completed as soon as April.

After that, AstraZeneca could then be able to apply for emergency use authorization from the U.S. Food and Drug Administration (FDA).

A vial of AstraZeneca COVID-19 vaccine
A vial of AstraZeneca COVID-19 vaccine in Saxony during the coronavirus pandemic on March 15, 2021 in Dippoldiswalde, Germany. More than 15 European countries have suspended its use, amid fears over blood clots. Jens Schlueter/Getty Images

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This article has been updated with a graphic by Statista.