The risk of blood clots is higher after infection with the SARS-CoV-2 virus than after immunisation with Pfizer and AstraZeneca Covid-19 vaccines, according to a study The risk of developing adverse events such as blood clots is considerably higher after infection with the SARS-CoV-2 virus than after immunisation with Pfizer and AstraZeneca COVID-19 vaccines, according to a large UK study published in the British Medical Journal (BMJ) on Friday. The team led by researchers at the University of Oxford in the UK conducted the study on thrombocytopenia — a condition with low platelet counts — and thromboembolic events or blood clots following COVID-19 vaccination with Oxford-AstraZeneca and Pfizer-BioNTech preventives. Some of these events have led to restricted use of the Oxford-AstraZeneca vaccine, known as Covishield in India, in a number of countries. The researchers compared rates of adverse events after vaccination with rates of the same events after a positive SAR...