A study of autopsy findings of the first 12 patients who died of COVID-19 in a hospital in Hamburg, Germany, has found that 7 (58%) of them had undiagnosed deep vein thrombosis, suggesting that the virus may cause abnormal blood clotting.In the prospective cohort study, published yesterday in the Annals of Internal Medicine, researchers discovered that the direct cause of death in four patients was massive pulmonary embolism from deep vein blood clots in the legs that lodged in a lung artery, causing a blockage.High viral RNA loads, abnormal lung findingsHigh concentrations of COVID-19 genetic material were detected in the lungs, and also in the liver, kidney, or heart in five of six patients who had moderate viremia (COVID-19 viruses in