Lung and leg clots were much more likely in seriously ill patients, but mild cases can be affected.
After a Covid infection, there is an increased risk of developing a serious blood clot for the next six months, a study from Sweden suggests.
When the researchers compared the risks of blood clots after Covid to the normal level of risk, they found that: The study, published in the BMJ, said the raised risk of blood clots was higher in the first wave than later waves, probably because treatments improved during the pandemic and older patients were starting to be vaccinated by the second wave.
The researchers can't explain exactly why these blood clots happen after Covid, but they have several theories. It could be the direct effect of the virus on the layer of cells which line blood vessels, an exaggerated inflammatory response to the virus, or the body making blood clots at inappropriate times.