LONDON (Reuters) – There is a much higher risk of blood clots caused by COVID-19 infection than vaccines against the disease, British researchers said on Thursday, after the launch of inoculations was interrupted by reports of rare clots.
AstraZeneca and Johnson & Johnson have both seen very rare reports of venous sinus thrombosis related to their vaccines. On Wednesday, the United States stopped vaccinations using J & J’s shot while a clot connection was being investigated, with Denmark abandoning AstraZeneca’s shot on the issue.
The UK and European regulators have emphasized that the benefits of vaccination outweigh the risks.
A study of 500,000 patients with COVID-19 found that CVST occurred at a rate of 39 people in a million after infection, the researchers said. This compares with figures from the European Medicines Agency, which shows that 5 out of one million people reported CVST after AstraZeneca was shot.
The researchers said in a pre-printed study that the risk of CVST was 8-10 times higher after COVID-19 infection than in existing vaccines for the disease.
“The risk of having a (CVST) after COVID-19 appears to be substantially and significantly higher than after the Oxford-AstraZeneca vaccine,” Maxime Taquet of the Oxford Department of Psychiatry told reporters.
The study was based on a US health database and therefore did not accumulate new data on the risk of clots forming from the AstraZeneca vaccine directly because the shot is not fired there.
Taquet said the CVST mortality rate was about 20%, regardless of whether it occurred after COVID-19 infection or a vaccine, indicating that clots were the main risk factor.
A new study from Oxford shows that the risk of rare blood clotting (CVD) is several times higher after contracting # COVID-19 than is post-vaccination.
CVD is also 100 times more likely to occur after COVID-19 than normal.
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– University of Oxford (@UniofOxford) April 15, 2021
Regulators also noted low platelet levels in reports of vaccine side effects, but researchers said data is limited on the fact that this was also the case for those who report CVST after infection.
The researchers pointed out that COVID-19 has been associated with more common clotting disorders than CVST, such as stroke, and that recent debates about vaccines have lost sight of how bad the disease itself could be.
“The importance of this finding is that it brings it back to the fact that it is a truly horrible disease, as a whole variety of effects, including an increased risk of (CVST),” said John Geddes, director of the NIHR Oxford Health Biomedical Research Center. .
The research team at Oxford University said it worked independently of the Oxford vaccine team that developed the AstraZeneca shot.
(Reporting by Alistair Smout; Editing by Bernadette Baum)
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