More research is still needed to fully understand the risks though.
Researchers at the University of Oxford have today reported that the risk of the rare blood clotting known as cerebral venous thrombosis (CVT) is around 100 times greater after coronavirus infection.
They studied over 500,000 COVID-19 patients and say 30% of cases occurred in people in the under 30s.
Compared to the Oxford/Astrazeneca vaccine, the risk of CVT from covid-19 is about 8 times greater, according to the study.
CVT has been reported to occur in about 5 in a million people after first dose of the Oxford COVID-19 vaccine.
The experts have reported that the risk is about 10 times greater if you have the mRNA vaccines.
Paul Harrison, Professor of Psychiatry and Head of the Translational Neurobiology Group at the University of Oxford, said: 'There are concerns about possible associations between vaccines, and CVT, causing governments and regulators to restrict the use of certain vaccines. Yet, one key question remained unknown: 'What is the risk of CVT following a diagnosis of COVID-19?'.
'We've reached two important conclusions. Firstly, COVID-19 markedly increases the risk of CVT, adding to the list of blood clotting problems this infection causes. Secondly, the COVID-19 risk is higher than see with the current vaccines, even for those under 30; something that should be taken into account when considering the balances between risks and benefits for vaccination.'
Dr Maxime Taquet, also from the Translational Neurobiology Group, said: 'It's important to note that this data should be interpreted cautiously, especially since the data on the Oxford-AstraZeneca vaccine come from UK MHRA monitoring, whereas the other data uses the TriNetX electronic health records network. However, the signals that COVID-19 is linked to CVT, as well as portal vein thrombosis - a clotting disorder of the liver - is clear, and one we should take note of.'
All comparisons must be interpreted cautiously since data are still accruing, according to the report authors.