In response to an infection like COVID-19, the body initiates several defense mechanisms including an inflammatory response. Blood clotting is a normal response, not inherently bad. However, serious or chronic inflammation can lead to the formation of dangerous blood clots. Factors associated with severe cases of COVID-19 such as oxygen deprivation and immobilization further increase the risk of dangerous blood clot formation.
In a study of ICU patients with COVID-19, 31% developed clotting complications. Due to this high incidence, experts are now recommending stronger preventative steps for all COVID-19 patients in the ICU.