In this study, we investigated the association between coagulation markers (α2AP, plasminogen, TAFI, tPA, PAI-1, D-dimer, and fibrinogen) and various changes in the fibrinolytic system in a cohort of COVID-19 patients, as well as the severity of the disease based on disease stage and whether these patients were admitted to the ICU. The gene discussed is SERPINE1; the disease is COVID-19.