COVID-19 bigger blood clot threat than vaccines, UK study finds

A coronavirus infection presents a much higher risk of developing a blood clot than the first dose of either the Oxford/AstraZeneca or the Pfizer/BioNTech jab, a large study led by the University of Oxford said on Friday.

The research used findings from more than 29 million people who were vaccinated with the first doses of either vaccine between December 2020 and April 2021.

The findings showed although there was an increased risk of having a blood clot after having the first doses of either vaccine, it was much greater in someone who had tested positive for COVID-19 caused by the SARS-CoV-2 virus.

“People should be aware of these increased risks after COVID-19 vaccination and seek medical attention promptly if they develop symptoms, but also be aware that the risks are considerably higher and over longer periods of time if they become infected with SARS-CoV-2,” said Julia Hippisley-Cox, Professor of Clinical Epidemiology and General Practice at the University of Oxford and lead author of the paper.

The study covered thrombocytopenia – a condition with low platelet counts – and thromboembolic events (blood clots) following vaccination for COVID-19, some of the same events which had led to restricted use in a number of countries of the Oxford/AstraZeneca vaccine – being produced and administered in India as Covishield.