The odds of a clot are highest for the most critically ill patients. Analysis of 66 studies found that 23% of COVID-19 patients in an intensive care unit (ICU) developed a blood clot in the leg, known as a deep vein thrombosis (DVT). Overall prevalence of a DVT was 14% among ICU and non-ICU COVID-19 patients, and 8% among those with mild-to-moderate disease risk who were not admitted to the ICU.