EU Agency Finds Astrazeneca Vaccine Can Cause Rare Blood Clots

European drug regulators have confirmed a link between the Oxford-AstraZeneca Covid-19 shot and rare blood clots, as UK authorities recommended that people under 30 should take alternative vaccines.

The European Medicines Agency (EMA) said Wednesday that a particular combination of unusual blood clots with low blood platelet counts should be listed as a side effect of the vaccine, but stopped short of recommending its use be limited. The benefits of the shot outweigh the risks and Covid-19 is a “very serious disease,” it added.

UK regulators took a more cautious approach, saying healthy adults under 30 should be offered other vaccines. Officials described the move as a “course correction” that would not derail the country’s rapid inoculation program.

The findings could have enormous implications for developing and middle-income countries, many of which are accessing the AstraZeneca shot through Covax, a vaccine-sharing scheme.

EMA officials said they looked at 18 deaths in their analysis. These fatalities were reported in 62 cases of clotting in the sinuses that drain blood from the brain, and 24 cases of clotting in the abdomen. The cases were reported in an EU safety database from European countries, including the UK, where around 25 million people in total had received the AstraZeneca vaccine.

“First of all, I want to start by stating that our safety committee (the Pharmacovigilance and Risk Assessment Committee or PRAC) … has confirmed that the benefits of the AstraZeneca vaccine in preventing Covid-19 overall outweigh the risks of side effects,” EMA Executive Director Emer Cooke told a press conference.

PRAC chair Sabine Straus reiterated the cases of severe clotting with low blood platelet counts were extremely rare but conceded, when challenged by journalists, that EMA did not have the data to understand the extent to which benefits might still outweigh risks for particular groups, by age or sex, for example.

“At the moment that’s something that’s very difficult to answer because the clinical trials … we do not have all the age stratified data available,” said Straus, adding that the agency planned to obtain that data and undertake further analysis.

Cooke said there was no clear risk profile found when the safety committee looked at the age and sex of people reporting these rare adverse reactions, even though a statement published by EMA earlier made clear most of the cases reported “occurred in women under 60 years of age within 2 weeks of vaccination.”

EMA’s statement called on healthcare workers 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 2 weeks of vaccination.”