Purple rashes, swollen legs, clogged catheters and sudden death—blood clots, large and small, are a frequent complication of COVID-19, and researchers are just beginning to untangle why. For weeks, reports have poured in of the disease’s effects throughout the body, many of which are caused by clots. “This is like a storm of blood clots,” Why this clotting occurs is still a mystery. One possibility is that SARS-CoV-2 is directly attacking the endothelial cells that line the blood vessels. Endothelial cells harbour the same ACE2 receptor that the virus uses to enter lung cells. And there is evidence that endothelial cells can become infected In healthy individuals,the blood vessel is “a very smoothly lined pipe”, The lining actively stops clots from forming. But viral infection can damage these cells, prompting them to churn out proteins that trigger the process. The virus’s effects on the immune system could also affect clotting. In some people, COVID-19 prompts immune cells to release a torrent of chemical signals that ramps up inflammation, which is linked to coagulation and clotting through a variety of pathways. And the virus appears to activate the complement system, a defence mechanism that sparks clotting.
Ref Credit and Soure of Information https://www.nature.com/articles/d41586-020-01403-8?error=cookies_not_supported&code=f91e8c8a-0d29-488d-9a1f-502b210856b3