A statement published online read: “The EMA’s safety committee has concluded today that unusual blood clots with low blood platelets should be listed as very rare side effects of the COVID-19 AstraZeneca vaccine.”

The EMA added however that the benefits of the vaccine outweigh the risks.

Emer Cooke, EMA's Exec. Director: "EMA’s expert committee on the safety of medicines (#PRAC) has confirmed that the benefits of the AstraZeneca vaccine in preventing #COVID19 overall outweigh the risks of side effects.”

— EU Medicines Agency (@EMA_News) April 7, 2021

While millions of doses of the vaccine developed with Oxford University have been administered, small numbers of people have developed deadly blood clots, which prompted countries including the European Union’s three largest nations – Germany, France and Italy – to temporarily suspend injections pending the EMA investigation.

In March the EMA said the vaccine was “safe and effective” in protecting people against Covid-19 but that it couldn’t rule out a link to blood clots, and that more investigations were needed.

On Wednesday the EMA said the AstraZeneca vaccine should continue to be used for all age groups but that people should be told of the possible rare side effects. The announcement came as the UK’s own drugs regulator said the AZ vaccine should now only be given to over 30s.

The EMA said it was “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.”

Sabine Straus, PRAC Chair: “It is of great importance that #healthcareprofessionals and the people coming for vaccination are aware of these risks and look out for possible signs or symptoms that usually occur in the first two weeks following vaccination.”

— EU Medicines Agency (@EMA_News) April 7, 2021

One plausible explanation for the combination of blood clots and low blood platelets is an immune response, the EMA said but that it had not identified any clear risk factors for causing the clots including age or gender.

So far, most of the cases reported have occurred in women under 60 years of age within two weeks of vaccination. 

The EMA advised that people who have received the vaccine should seek medical assistance immediately if they develop symptoms of this combination of blood clots and low blood platelets.

Symptoms include shortness of breath, chest pain, swelling in legs, abdominal pain, severe headaches, blurred vision and tiny blood spots under the skin at the sight of the injection.

The EMA 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 EU drug safety database (EudraVigilance) as of 22 March 2021, 18 of which were fatal

The agency concluded: “COVID-19 is associated with a risk of hospitalisation and death. 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.”

Germany, France and Italy have all restarted AstraZeneca vaccines, but in the case of France and Germany with extra guidelines on the age of patients it should be used for. France is currently not administering the AstraZeneca vaccine to under 55s or over 75s.