A large study of rare blood clots linked to AstraZeneca’s COVID-19 vaccine found between one and three cases per million, and only after the first dose, shedding new light on vaccine side effects.
Researchers have tried to analyze any link between COVID-19 vaccines and rare blood clots in the brain, arteries or veins, sometimes accompanied by low platelets, reports that led many nations last year to suspend the use of the AstraZeneca injection, which was developed with the University of Oxford.
A study published in the journal PLOS Medicine on Tuesday analyzed the health records of 46 million adults in England between December 2020 and March 2021 to assess the risk of clots in the month after vaccination with the Pfizer-BioNTech vaccine or AstraZeneca-Oxford, compared to the unvaccinated.
It was conducted by William Whiteley of the University of Edinburgh and Britain’s BHF Data Science Center.
It found no risk of major arterial and venous thrombotic events in people aged 70 years and older with either vaccine.
And while the risk of intracranial venous thrombosis (IVT) after the AstraZeneca-Oxford vaccine was almost double in those under 70, that was between one and three cases per million.
The risks of IVT and hospitalization for thrombocytopenia “are likely to be outweighed by the effect of vaccines in reducing COVID-19 mortality and morbidity,” the study authors said.
The rare blood clot cases emerged early last year as the AstraZeneca-Oxford vaccine began its rollout in Europe.
Johnson & Johnson’s vaccine, which is based on a similar platform to AstraZeneca-Oxford’s injection, has also been associated with the rare combination of blood clotting and low platelet counts.
Some countries have restricted or suspended use of the vaccines after the EU medicines regulator confirmed possible links between the injections and the conditions. International drug regulators have said that the benefits of vaccines outweigh the risks.
Source: Gestion
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