SARS-CoV-2 has become one of the most important and challenging medical research topics in recent years. The presence of endothelial dysfunction, immune thrombosis, and oxidative stress contributes to complications and requires more extended hospitalisation of patients. In this article, we focused on analysing the impact of oxidative stress on the severity of COVID-19 infection. The study group consisted of 72 patients with laboratory-confirmed SARS-CoV enrolled. The patients were divided into moderate and severe diseases according to the SCRI (Simple Covid Risk Index, including lymphocyte/D-dimer ratio). Using the ELISA kit, we determined the level of AOPP and 8-OHdG. Patients with severe COVID-19 had higher levels of both AOPP (P < 0.05) and 8-OHdG (P < 0.05) compared to patients with moderate disease. Albumin levels were significantly lower (P < 0.001), although fibrinogen (P < 0.01), D-dimer (P < 0.001), and TF (P < 0.05) levels were higher in severe patients than in moderate course. AOPP/Alb was also higher among severe patients (P < 0.05). Our data suggest a potential role for AOPP and 8-OHdG in predicting the outcome of SARS-CoV-2 patients. Elevated AOPP levels were associated with increased Dimer-D, TF, and vWF activity levels.