The European Union’s medical regulator said Wednesday that rare, but sometimes deadly blood clots, are a potential side effect of AstraZeneca’s coronavirus vaccine. But it continues to say the benefits of the vaccine outweigh any risks as thousands die of coronavirus across Europe each day.

In Britain, June Raine, chief executive officer of the Medicines and health care Products Regulatory Agency, said there was a “reasonably plausible link” between the AstraZeneca and these “extremely rare” blood clots.

Most of the cases reported have occurred in women under 60 years of age. The agency said it still has been unable to work out if particular groups were more at risk than others.

France, Germany, Sweden and Canada are among those restricting its use in younger people, while Denmark and Norway have maintained a complete pause.

AstraZeneca has said that patient safety remains its highest priority and that it is analyzing its databases of tens of millions of patients to better understand whether there is a higher rate of the clots than might otherwise be expected.

The AstraZeneca vaccine, developed in collaboration with the University of Oxford, has not been approved for use in the United States, but doses have been bought.

More European countries said on March 15 they would hit pause on AstraZeneca's coronavirus vaccine after reports of possible serious side-effects. (Reuters)