Possible new links between AstraZeneca coronavirus vaccine and blood clots identified

A study by scientists from US and UK universities identified possible reasons for the rare side effect, but company says the ‘research is not definitive’

Clots more common after first dose than second, with 426 cases reported to the UK from more than 24 million first and second shots given

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The Astra Zeneca coronavirus vaccine was linked to rare blood clots. Photo: Reuters.

Published: 7:01pm, 2 Dec 2021Updated: 9:53am, 3 Dec 2021

Scientists have identified a possible reason the AstraZeneca Covid-19 vaccine may cause blood clots, after use of the shot was limited globally to prevent the rare side effect.

The preclinical research, conducted with AstraZeneca, found the interaction between the vaccine and a protein known as platelet factor 4 could be behind the cases of thrombosis with thrombocytopenia syndrome, according to a study published on Wednesday in the journal Science Advances by scientists from US and UK universities, as well as AstraZeneca.

The research is not definitive, the company said.

The AstraZeneca vaccine, co-developed with the University of Oxford, has been hampered globally by a possible link between the shot and rare cases of blood clots, with the UK limiting its use to those over 40 and the US yet to authorise the vaccine.

In May, German scientists published a hypothesis that the side effect was linked to the adenovirus vector the inoculation uses.

The clots have been more common after a first dose than second, with 426 cases reported to the UK regulator as of November 17 from more than 24 million first and second shots given.