Virus poses bigger risk of clots than AstraZeneca jab, says study
The clot risk from getting Covid is at least eight times greater than that from AstraZeneca jab, research by Oxford University suggests.
The study of half a million Covid19 patients found that, overall, getting the virus increased the chance of cerebral venous thrombosis (CVT) 100-fold, compared with the risk for those without coronavirus.
In total, 39 in a million Covid patients suffered the clot, compared with rates of five in a million for those given the AstraZeneca jab and four in a million for those who had Pfizer or Moderna.
Last week, Britain’s Joint Committee on Vaccination and Immunisation changed its advice, to say under-30s should be offered an alternative jab to AstraZeneca.
The new research is the first major study to show how much greater the risk is from getting Covid. It found that the trend was similar across all age groups, with almost one third of clots in Covid patients occurring in the under-30s.
Yesterday, Professor Anthony Harnden, JCVI deputy chairman, said reported cases of clotting among recipients of the Johnson & Johnson jab may suggest that any link is common to all adenoviral vector vaccines, rather than peculiar to AstraZeneca.
He told a Royal Society of Medicine seminar: “It’s only a strong possibility that it’s linked to the vaccine, but it’s looking increasingly likely that it’s a viral vector platform effect rather than a vaccinespecific effect.”
Lead researcher Professor Paul Harrison, head of the Translational Neurobiology Group at the
University of Oxford, said the latest study provided crucial information about data which had so far been lacking from the debate.
He said: “We’ve reached two important conclusions. Firstly, Covid markedly increases the risk of CVT, adding to the list of clotting problems this infection causes.
“Secondly, the Covid risk is higher than seen with the vaccines, even for those under 30; something that should be taken into account when considering the balances between risks and benefits for vaccination.”