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Safety review shows ‘no evidence’ that AZ's vaccine causes increased risk of blood clots

AZ's vaccine continues to be backed by the EMA and the EMA’s Pharmacovigilance Risk Assessment Committee

British drugmaker AstraZeneca (AZ) has said findings from its safety review showed no evidence of a link between its COVID-19 vaccine and an increased risk of blood clots.

In a review of all available safety data from over 17 million people vaccinated with the AZ vaccine in the EU and UK, no evidence of an increased risk of pulmonary embolism, deep vein thrombosis (DVT) or thrombocytopenia was discovered.

This finding covered any defined age group, gender, batch and any particular country, AZ said in a statement issued yesterday.

The company added that, as of 8 March, it has received reports of 15 DVT events and 22 pulmonary embolism events among those given its vaccine across the EU and UK.

According to AZ, this figure is ‘much lower’ than the number of cases that would be expected to occur naturally in a general population of this size, and is also similar across other licensed COVID-19 vaccines.

In clinical trials of AZ’s COVID-19 vaccine, the number of thrombotic events was small and lower in the vaccinated group, with ‘no evidence of increased bleeding in over 60,000 participants enrolled’.

“Around 17 million people in the EU and UK have now received our vaccine, and the number of cases of blood clots reported in this group is lower than the hundreds of cases that would be expected among the general population,” said Ann Taylor, chief medical officer of AZ.

“The nature of the pandemic has led to increased attention in individual cases and we are going beyond the standard practices for safety monitoring of licensed medicines in reporting vaccine events, to ensure public safety,” she added.

A number of countries have halted the use of AZ’s vaccine as a precautionary measure in response to the reported cases of blood clots in people who have received the jab.

This includes Denmark, Norway, Iceland, the Netherlands, Bulgaria and Ireland, while additional countries have reportedly suspended the use of certain batches of AZ’s vaccine.

Last week, the European Medicines Agency (EMA) said that there is currently ‘no indication’ that the reported blood clots were caused by AZ’s vaccine.

The EMA’s Pharmacovigilance Risk Assessment Committee (PRAC) has maintained that the benefits of the AZ/Oxford vaccine continue to outweigh the risks.

It added that the vaccine can still be administered while the ongoing investigation into the cases of thromboembolic events continues.

This stance was echoed by the UK Medicines and Healthcare products Regulatory Agency’s  (MHRA) vaccines safety lead Phil Bryan, who commented: “We are keeping this issue under close review but available evidence does not confirm that the vaccine is the cause [of reported blood clots]. People should still go to get their COVID-19 vaccine when asked to do so.”

The World Health Organization’s (WHO) Global Advisory Committee on Vaccine Safety is also carefully assessing the blood clot reports.

“It is important to note that the EMA has said there is no indication of a link between the vaccine and blood clots, and that the vaccine can continue to be used while its investigation is ongoing,” said WHO director-general Tedros Adhanom Ghebreyesus.

“More than 335 million doses of COVID-19 vaccines have been administered globally so far, and no deaths have been found to have been caused by COVID-19 vaccines,” he added.

Article by
Lucy Parsons

15th March 2021

From: Research



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