AstraZeneca: Blood clots are 'very rare' side effect of Covid vaccine and benefits outweigh risk, EMA rules

  • Video report by ITV Science Editor Tom Clarke

The EU medicines regulator has ruled that blood clots are a "very rare" side effect of the AstraZeneca/Oxford Covid-19 vaccine and the benefits still outweigh the risks.

Amid fresh concerns over whether the jab could cause blood clots, the European Medicines Agency (EMA) said that as of April 4, the EU's drug safety database recorded 169 cases of clots in the brain (cerebral venous sinus thrombosis or CVST) and 53 of clots in abdomen.

At the time, about 34 million people were vaccinated in the European Economic Area and the UK.

Sabine Straus, chair of the EMA's safety committee Pharmacovigilance and Risk Assessment Committee (PRAC), said: "Our conclusion is that this clotting disorders are very rare side effects of the vaccine."

But she also said the EMA could not conclude whether there were increased risks of rare blood clots in younger people.

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She said most of the cases of blood clots reported occured in women under 60 within two weeks of vaccination, but "some of that could be explained by the way that the vaccine is being used in the EU and the European Economic Area".

Thus, the EMA could not conclude on specific risk factors, such as age, gender or previous history of clotting disorders.

Despite this, the UK's Medicines and Healthcare products Regulatory Agency (MHRA) announced on Wednesday afternoon that under-30s in the UK will be offered Pfizer or Moderna vaccines rather than the Oxford/AstraZeneca vaccine due to concerns over the rare risk of blood clots.

Dr Straus said people should look out for the following blood clot symptoms within the first two weeks of getting the jab: shortness of breath, chest pain, swelling in the leg, persistent abdominal pain, severe headaches, blurred vision and tiny blood spots under the skin beyond the area where the injection was administered.

AstraZeneca vaccine trials for children have been halted. Credit: ITV News

The EMA could not yet identify a definite cause for the clots, but a plausible explanation is that they could be an immune reponse that seems similar to a condition called atypical heparin induced thrombocytopenia, Dr Straus said.

The committee carried out a review of 62 cases of clots in the brain (cerebral venous sinus thrombosis or CVST) and 24 cases of clots in the abdomen as of March 22, with 18 of the cases proving fatal.

The cases were reported from the European Economic Area and the UK, from around 25 million people who had received the vaccine.

EMA executive director Emer Cooke said during the Brussels press briefing on Wednesday that the agency's Pharmacovigilance and Risk Assessment Committee (PRAC) confirmed "the benefits of the AstraZeneca vaccine in preventing Covid-19 overall outweigh the risks of side effects".

She continued: “Covid-19 is a very serious disease with high hospitalisation and death rates and everyday Covid is still causing thousands of deaths across the EU.

“This vaccine has proven to be highly effective – it prevents severe disease and hospitalisation, and it is saving lives.

“Vaccination is extremely important in helping us in the fight against Covid-19 and we need to use the vaccines we have to protect us from the devastating effects.

“The PRAC after a very in-depth analysis, has 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.”

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MHRA chief executive Dr June Raine likewise said the benefits of the AstraZeneca vaccine outweigh the risks for the “vast majority” of people after cases of blood clots were detected in an “extremely small” number of people.

A trial of the UK's main coronavirus vaccine on around 300 children was paused on Tuesday while the MHRA investigated the possibility of links to a rare blood clotting syndrome in adults.

The University of Oxford said that no safety concerns had arisen from the trial itself but decided to pause the trial ahead of the ruling from the MHRA.

A number of European countries, including Holland, have restricted use of the vaccine in younger people after reports of CVST, a specific type of clot that prevents blood from draining from the brain.

Health ministers from the 27 European Union member states will meet to discuss regulators' findings on the AstraZeneca vaccine later on Wednesday.

The World Health Organization is also investigating blood clot links with the vaccine and will provide an update this week.

In the latest MHRA update, 30 cases of CVST and seven deaths were reported in the UK among more than 18.1 million people receiving the jab.

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