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27 August 2021updated 09 Sep 2021 6:40am

Covid-19 is far more likely to cause blood clots than the AstraZeneca vaccine

A new study shows that someone with coronavirus is 12.9 times more likely to get vein blood clots and 12.43 times more likely to get brain blood clots.

By Katharine Swindells

Earlier in the year, the Oxford-AstraZeneca vaccine faced a reputational crisis, with a number of recently vaccinated people across Europe experiencing blood clots. As a result, the UK and several other countries in Europe placed age restrictions on the vaccine, and it has still not been approved for use in the United States.


Covid-19 is far more likely to cause blood clots than the AstraZeneca vaccine
Increase in likelihood of blood clot occurence compared to normal

But a new study published in the British Medical Journal yesterday, which used patient data from over 30 million people in England, shows that while there is some risk of blood clotting among those with the AstraZeneca vaccine, it is still far lower than the risk among those who test positive for Covid-19.

In the 28 days following the first dose of Oxford-AstraZeneca, people are 10 per cent more likely to get vein blood clots than the average pre-pandemic person, and three times more likely to get brain blood clots.

In comparison, in the 28 days following a positive Covid-19 test, a person is 12.9 times more likely to get vein blood clots, and 12.43 times more likely to get brain blood clots.

“People should be aware of these increased risks after Covid-19 vaccination and seek medical attention promptly if they develop symptoms,” says Julia Hippisley-Cox, the Oxford epidemiologist who led the study. “But also be aware that the risks are considerably higher and over longer periods of time if they become infected with Covid-19.”

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