Micro Clots & Long COVID
July 25, 2023
One of the leading theories used to explain Long Covid symptoms involves micro clots. A publication in Nature last August tackled the topic. Researchers have observed abnormal clots in the blood of people with COVID-19 and Long Covid. The clots are very small and break down slowly. The theory is that the viral spike protein binds to fibrin (a clotting protein) and causes it to misfold into a stickier version called amyloid. This may cause a cascade effect where more fibrin misfolds and more amyloid micro clots are formed. Microclots can slow down and restrict blood flow perhaps resulting in Long Covid symptoms. Researchers have even found that micro clots can cause capillaries to split in order to reroute blood around a blockage.
Micro clots are not unique to Long Covid or COVID-19 infections; they have been observed in a variety of conditions: diabetes, Alzheimer’s disease, Parkinson’s disease, and Myalgic Encephalomyelitis /Chronic Fatigue Syndrome (1) (2). However, relatively little research has been done on micro clots, and much is still unknown. There is conflicting evidence on whether micro clots are even a cause of symptoms.
The results of one clinical trial on using antiplatelet and anticoagulants to treat Long Covid were promising: patients had fewer micro clots and experienced some symptom relief. Additionally, levels of microclots have been seen to correlate with fatigue (3). However, some experts find that evidence for micro clots causing Long Covid is lacking. Some researchers have been unable to find micro clots in the blood of Long Covid patients, and others did not observe the expected anemia and tissue damage to the lungs and kidneys (organs with lots of capillaries that could become blocked) that such clots would cause. They argue that more research is needed before trialing pharmaceutical therapies.
Fortunately, research on Long Covid is ongoing. There are currently no clinical trials of anticoagulants for Long Covid listed on the clinicaltrials.gov website, but this may change as new studies are released. The Global Autoimmune Institute is proud to fund one such study: The Long Covid PASC study at Johns Hopkins Čiháková research laboratory. Such research is crucial to understanding this disease and developing treatments.