No evidence of vaccine increasing blood clot risk: AstraZeneca

By Jane Byrne

- Last updated on GMT

© GettyImages/
© GettyImages/

Related tags thrombosis blood clots

As more countries temporarily pause the use of the COVID-19 Vaccine AstraZeneca in their vaccination programs, the company stressed the safety of the jab, based on scientific evidence.

Germany, France and Italy are the latest countries to suspend the use of the shot. They all announced a temporary suspension of the use of the vaccine today. The Netherlands and Ireland also moved to pause the use of the AstraZeneca shot in their campaigns over the past few days, pending the results of the review by the European Medicines Agency (EMA).

On Sunday (March 14), AstraZeneca said careful review of all available safety data of more than 17 million people vaccinated in the EU and UK with the shot has shown no evidence of an increased risk of pulmonary embolism, deep vein thrombosis (DVT) or thrombocytopenia, in any defined age group, gender, batch or in any particular country.

“So far across the EU and UK, there have been 15 events of DVT and 22 events of pulmonary embolism reported among those given the vaccine, based on the number of cases the company has received as of March 8.

“This is much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed COVID-19 vaccines.

“Furthermore, in clinical trials, even though the number of thrombotic events was small, these were lower in the vaccinated group. There has also been no evidence of increased bleeding in over 60,000 participants enrolled.”

In terms of quality, there are also no confirmed issues related to any batch of COVID-19 Vaccine AstraZeneca used across Europe, or the rest of the world, added the company.

It said additional testing has, and is, being conducted by it and independently by European health authorities and none of these re-tests have shown cause for concern.

The regulator's perspective 

The EMA’s Pharmacovigilance Risk Assessment Committee (PRAC) is reviewing all cases of thromboembolic events, and other conditions related to blood clots, reported post-vaccination with COVID-19 Vaccine AstraZeneca.

Today the agency said that events involving blood clots, some with unusual features such as low numbers of platelets, have occurred in a very small number of people who received the vaccine. "Many thousands of people develop blood clots annually in the EU for different reasons. The number of thromboembolic events overall in vaccinated people seems not to be higher than that seen in the general population."

The regulator said it is working closely with the company, with experts in blood disorders, and with other health authorities including the UK’s MHRA based on its experience with around 11 million administered doses of the vaccine.

"EMA’s investigation has been continuing over the weekend, and rigorous analysis of all the data related to thromboembolic events will be carried out in the coming days. Experts are looking in great detail at all the available data and clinical circumstances surrounding specific cases to determine whether the vaccine might have contributed or if the event is likely to have been due to other causes. EMA’s safety committee, PRAC, will further review the information tomorrow and has called an extraordinary meeting on Thursday, March 18, to conclude on the information gathered and any further actions that may need to be take."

A World Health Organization (WHO) expert advisory committee is also currently reviewing the reports about blood clots; Friday (March 12) saw a spokeswoman for that body echo the statement of the EMA, saying there was no reason not to use the AstraZeneca vaccine. Margaret Harris told a media briefing that it was an “excellent vaccine”​ and that no causal relationship had been established between the jab and the health problems reported. 

The WHO-led global vaccine sharing scheme, COVAX, that aims to distribute 2 billion doses this year, ensuring access for poorer countries, relies heavily on the AstraZeneca vaccine to do so.

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