AstraZeneca Vaccine Side Effects List Should Include Blood Clots, European Officials Say

The European Medicines Agency (EMA), an EU regulatory body, said that AstraZeneca should list rare blood clots as a possible side effect of the pharmaceutical giant's COVID vaccine.

In a Wednesday media briefing, EMA Executive Director Emer Cooke said that after an in-depth analysis of the vaccine, the regulator had concluded "that the reported cases of unusual blood clotting following vaccination with the AstraZeneca vaccine should be listed as possible side effects of the vaccine."

Despite those possibilities, both the European regulator and the U.K.'s Medicines and Healthcare Products Regulatory Agency (MHRA) said the benefits of the vaccine outweigh the risks.

"The reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing COVID-19 outweigh the risks of side effects," the EMA said in a Wednesday statement.

MHRA chief June Raine said, "The balance of benefits and known risks of the vaccine is still very favorable for the vast number of people."

"COVID-19 is a very serious disease with high hospitalization and death rates and every day COVID is still causing thousands of deaths across the EU," Cooke added. "This vaccine has proven to be highly effective—it prevents severe disease and hospitalization, and it is saving lives."

In a statement Wednesday, the vaccine manufacturer said, "Overall, both of these reviews reaffirmed the vaccine offers a high level of protection against all severities of COVID-19 and that these benefits continue to far outweigh the risks."

The statement went on, "AstraZeneca has been actively collaborating with the regulators to implement these changes to the product information and is already working to understand the individual cases, epidemiology and possible mechanisms that could explain these extremely rare events."

A medical worker draws up a dose of the Oxford/AstraZeneca vaccine against the coronavirus disease, marketed under the name Covishield and produced in India, in a syringe during the vaccination of people in an outpatient clinic in Kiev on April 7, 2021. The European Medicines Agency said that the AstraZeneca vaccine should list blood clots as a possible side effect on Wednesday. Genya Savilov/AFP

Guidance for younger people as to whether or not they should get the AstraZeneca shot has shifted recently.

Most of the cases of blood clots that have been reported have occurred in women under 60 years of age within two weeks of vaccination. But the EMA's review has not yet determined a clear risk profile in the age and gender of those reporting such adverse reactions.

The EMA said its recommendations for use of the vaccine are not changing and called on those receiving the vaccine "to remain aware of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within 2 weeks of vaccination."

The European Union's medicine regulator said that one reasonable explanation for blood clots and low blood platelets, another rare side effect, is that "immune response, leading to a condition similar to one seen sometimes in patients treated with heparin (heparin induced thrombocytopenia, HIT)".

EMA's decision follows last week's news from Germany and Canada, which suspended the use of the AstraZeneca vaccine in people under 60 and 55, respectively.

Several European counties have resumed use of the vaccine after previously suspending it over concerns of blood clots. Among the countries that have restarted AstraZeneca immunizations are Austria, Bulgaria, France, Finland, Ireland, Italy, Latvia, Lithuania, Romania and Sweden. The vaccine continues to be suspended in Denmark and Norway.

This story was updated on April 7 with comments from AstraZeneca.

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