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EMA, WHO investigate reported clots with AstraZeneca vaccine

Posted 15 March 2021 | By Kari Oakes 

EMA, WHO investigate reported clots with AstraZeneca vaccine

As countries in Europe and elsewhere continue to pause administration of the AstraZeneca COVID-19 vaccines over reports of clotting events in recipients, the European Medicines Agency (EMA) announced Monday that it worked through the weekend to analyze and make sense of these reports.
 
Continuing a “rigorous analysis of all the data related to thromboembolic events,” EMA announced that its safety committee (PRAC) will hold an extraordinary meeting on Thursday, 18 March, “to conclude on the information gathered and any further actions that may need to be taken.”
 
EMA noted in the statement that some of the reports of blood clots involved “unusual features” such as low platelet counts in those affected. At the moment, though, EMA is maintaining the position it asserted before the weekend that the rate of thromboembolism in those receiving the vaccine is no higher than that seen in the general population. (RELATED: EMA offers reassurance on AZ vaccine, while some European authorities pause, Regulatory Focus 11 March 2021)
 
AstraZeneca went further in a statement issued Sunday. As of 8 March, the firm said that had received reports of a total of 37 thromboembolic events – 15 cases of deep venous thrombosis and 22 of pulmonary embolism – had been reported among recipients of its vaccine.
 
“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,” wrote the firm in its statement. Full details of the clotting events will be included in the monthly safety report AstraZeneca must submit to EMA as one of the terms of its conditional marketing authorization for the vaccine.
 
“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,” Ann Taylor, AstraZeneca’s chief medical officer, said.
 
The Norwegian Medicines Agency (NOMA) released a statement on Monday that highlighted three instances of “severe cases of blood clots, bleeding and low platelet counts” in people who had received the AstraZeneca vaccine; one of those patients has now died, and all three required hospital admission, according to the NOMA statement.
 
The clinical presentation of low platelet counts, bleeding, and clotting in both large and small vessels that was seen in these patients is “very unusual,” noted NOMA. The announcement also alluded to a similar clinical picture having been seen in other European countries.  
 
Norway, Spain, Italy, Sweden, Denmark, Iceland, the Netherlands, Ireland and France have all now paused administration of the vaccine, even as the World Health Organization (WHO) also continues to advise countries to continue administering the AstraZeneca vaccine as investigations are ongoing.
 
WHO’s vaccines safety committee is meeting Tuesday “as a precautionary measure” to conduct its own review of the data and has been in close contact with EMA, according to a Monday press briefing.
 
Global health authorities will have to sort out whether the incidence of thromboembolic events reported in AstraZeneca vaccine recipients rises above the expected incidence in the general population, estimated at 104 to 183 per 100,000 person-years for individuals of European ancestry in a 2015 review published in Nature Reviews Cardiology.
 
EMA is working closely with the UK’s Medicines and Healthcare products Regulatory Authority (MHRA) because of their extensive experience with the AstraZeneca product. More than 11 million AstraZeneca doses have gone into arms in the UK, and the number of blood clots reported in vaccine recipients there “is not greater than the number that would have occurred naturally in the vaccinated population,” according to a statement from MHRA vaccines safety lead Phil Bryan.
 
The European regulator advises that countries continue to stay the course, for now: “While its investigation is ongoing, EMA currently remains of the view that the benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalization and death, outweigh the risks of side effects [emphasis original].”
 
EMA announcement
 

 

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Tags: coronavirus, EMA, MHRA, WHO

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