Higher risk of clots from Covid-19 than from vaccines: UK study

LONDON: There is a much higher risk of brain blood clots from Covid-19 infection than there is from vaccines against the disease, British researchers said yesterday, after the roll-out of inoculations was disrupted by reports of rare clots.

AstraZeneca and Johnson & Johnson have both seen very rare reports of cerebral venous sinus thrombosis (CVST) linked to their vaccines. On Wednesday, the US paused vaccinations using J&J's shot while a link with clots was investigated, with Denmark ditching AstraZeneca's shot over the issue.

British and European regulators have stressed the vaccines' benefits outweigh the risks.

A study of 500,000 Covid-19 patients found CVST had occurred at a rate of 39 people out of a million following infection, researchers said. That compares with European Medicines Agency figures showing that five in a million reported CVST after getting AstraZeneca's shot.

The researchers said in a pre-print study that the risk of CVST was eight to 10 times higher after a Covid-19 infection than it was from existing vaccines.

"The risk of having a (CVST) after Covid-19 appears to be substantially and significantly higher than it is after receiving the Oxford-AstraZeneca vaccine," Oxford's Department of Psychiatry's Maxime Taquet told reporters.

The researchers said the recent debate around vaccines has lost sight of how bad the disease itself could be.

"The importance of this finding is it brings it back to the fact that this is a really horrible illness as there are a whole variety of effects, including increased risk of (CVST)," said director of NIHR Oxford Health Biomedical Research Centre John Geddes. - REUTERS