EU Regulator Endorses AstraZeneca Covid-19 Vaccine While Warning of 'Possible' Blood Clot Risk

The European Union's pharmaceutical regulatory agency on Wednesday endorsed continued use of the Oxford-AstraZeneca coronavirus vaccine for all adults, even while confirming a "possible link" to blood clots that, while "very rare," have killed a small number of people.

"Covid-19 is a very serious disease with high hospitalization and death rates, and every day [it] is still causing thousands of deaths across the E.U. This vaccine has proven to be highly effective. It is saving lives."
--Emer Cooke, EMA

The European Medicines Agency (EMA) said in a statement that its safety committee "concluded today that unusual blood clots with low blood platelets should be listed as very rare side effects of Vaxzevria," formerly called the Covid-19 Vaccine AstraZeneca.

"EMA is reminding healthcare professionals and people 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 two weeks of vaccination," the agency said.

"So far, most of the cases reported have occurred in women under 60 years of age within two weeks of vaccination," it continued. "Based on the currently available evidence, specific risk factors have not been confirmed."

The safety committee "noted that the blood clots occurred in veins in the brain (cerebral venous sinus thrombosis, CVST) and the abdomen (splanchnic vein thrombosis) and in arteries, together with low levels of blood platelets and sometimes bleeding," according to the statement.

"The committee carried out an in-depth review of 62 cases of cerebral venous sinus thrombosis and 24 cases of splanchnic vein thrombosis reported in the E.U. drug safety database (EudraVigilance) as of March 22, 2021, 18 of which were fatal," the statement continued. "The cases came mainly from spontaneous reporting systems of the EEA and the U.K., where around 25 million people had received the vaccine."

The statement noted that "Covid-19 is associated with a risk of hospitalization and death," and concluded that "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."

According to AstraZeneca, its vaccine is 76% effective at reducing the risk of symptomatic Covid-19, and has shown 100% efficacy in preventing severe cases of the disease in an analysis of a large U.S. clinical trial.

EMA Executive Director Emer Cooke said at a Wednesday press conference that "Covid-19 is a very serious disease with high hospitalization and death rates, and every day [it] is still causing thousands of deaths across the E.U."

"This vaccine has proven to be highly effective," she said of the Oxford-AstraZeneca immunization. "It is saving lives."

The EMA endorsement came as the United Kingdom and parts of Spain on Wednesday joined France, Germany, and Italy in limiting who is eligible to receive the Oxford-AstraZeneca vaccine. People under the age of 30 will be offered alternative vaccine options in the U.K., while the Spanish region of Castile and Leon suspended all Oxford-AstraZeneca injections pending the outcome of an EMA safety report.

The U.K.'s move came after the nation's Medicines and Healthcare products Regulatory Agency (MHRA) found that by the end of March, 79 people had suffered post-vaccination blood clots, 19 of which resulted in patients' deaths.

More than 20 million doses of the Oxford-AstraZeneca vaccine have been administered in the U.K., making the odds of developing a blood clot after the jab about four in one million and the odds of death at about one in a million.

By contrast, Covid-19 kills about one in eight infected people aged 75 or older, and about one in 1,000 symptomatic infected people in their 40s, according to the BBC.