F2 and COVID-19: Increased activation of the coagulation system in the initial phase of COVID-19, which manifests as a higher concentration of D-dimers, a decreased number of platelets, and slightly prolonged prothrombin time, seems to be caused by the interaction between MASP-1, MASP-2, and thrombin, which could explain the coexistence of DIC syndrome in the early stages of COVID-19.