Here's an interesting paper about long covid. They hypothesized that some of the symptoms might be caused by the persistence of microclots. They took samples of plasma from healthy controls, people with long covid, people with acute covid, and those with T2 diabetes as a control inflammatory condition that is different from covid.
They did several tests and found anomaly. Normally excess clots are supposed to be broken down through a process called fibrinolysis, but in both the acute covid and long covid patients, they found protein aggregates in their blood plasma were resistant to being broken down. These aggregates were not found in the normal controls or the T2D people.
They even had a blood sample of one person before they got long covid, and found an increase in these protein aggregates after long covid had set in.
An analysis of the protein clumps found them to contain various clotting factors, and also complement proteins, which are part of the immune system that tries to clear clumps like this from the bloodstream. They also found alpha 2 antiplasmin embedded in the clumps. This is a protease inhibitor that might account for the inability to clear the clumps.
The authors suggest that perhaps anticoagulants would help. There are also thrombolytic (clot-busting) therapies. It's good to see interesting avenues of research in this area.
Link to study : https://www.medrxiv.org/content/10.1101/2021.05.21.21257578v1.full.pdf