There was a lot of talk at the time as to whether COVID should be classed as respiratory or a blood disorder. This seems to be quite a decent and updated article about it.

https://www.bhf.org.uk/informationsupport/heart-matters-maga...

> But as the outbreak progressed, case studies began to suggest that some of the most severe complications of the disease affected more than just the lungs. From reports of ‘sticky blood’ raising the risk of deep vein thrombosis, heart attack or stroke, to neurological effects, many complications seemed to be affecting the blood vessels.

[and yes I am ignoring the common implication of comments like that]