Risk of rare blood clotting higher for COVID-19 than for vaccines

Risk of rare blood clotting higher for COVID-19 than for vaccines

A new study has reported that the risk of the rare blood clotting known as cerebral venous thrombosis (CVT) following COVID-19 infection is around 100 times greater than normal, and several times higher than it is post-vaccination or following influenza.

The study authors, led by Professor Paul Harrison and Dr Maxime Taquet from the NIHR Oxford Health Biomedical Research Centre, counted the number of CVT cases diagnosed in the two weeks following diagnosis of COVID-19, or after the first dose of a vaccine. They compared these to cases of CVT following influenza, and the level in the general population.

They report that CVT is more common after COVID-19 than in any of the comparison groups, with 30% of these cases occurring in the under 30s. Compared to the current COVID-19 vaccines, this risk is between 8-10 times higher, and compared to the baseline, approximately 100 times higher.

Read the full story on the Oxford Health Biomedical Research Centre website.

Published: 19 April 2021