A recent study published in the journal Blood Advances found elevated levels of blood clotting markers in more than one in two (55%) people with long COVID who also had abnormal exercise testing results.
Dr. Resia Pretorius and her team in South Africa have written extensively about the link between Long COVID and micro-clotting. The presence of persistent micro-clots and hyperactivated platelets (also involved in clotting) perpetuates coagulation and vascular pathology, resulting in cells not getting enough oxygen in the tissues to sustain bodily functions (known as cellular hypoxia). Widespread hypoxia may be central to the numerous reported debilitating symptoms. Inside the micro clots that are present in these individuals' blood in circulation, there are various entrapped molecules, inflammatory molecules, that prevent the breakdown of the microclots.
One very important key point of importance in microclot formation in long COVID/PASC is that fibrinogen, too can, in the presence of various trigger substances, fold into an amyloid form that has a very different macrostructure characterized by different fiber diameters and pore sizes. This roque amyloid form of the prion protein is highly resistant to proteolysis. Amyloid will activate platelets and encourage more vascular inflammation and clotting.
Platelet activation can increase plasma Aβ levels and contribute to the pathogenesis of Alzheimer's disease; see: https://pubmed.ncbi.nlm.nih.gov/34371202/ Can platelet activation result in increased plasma Aβ levels and contribute to the pathogenesis of Alzheimer's disease?
This work in South Africa showed it is spike protein starting the micro clot process and Dr. Pretorius has said her findings are also seen in those with vaccine injuries.
These clots can induce autoantibodies and fuel further the autoimmune onslaught in PASC.