Proteins positively associated with a severe course of the COVID-19 disease (positive logFC), such as CRP, S100A8/A9 (detected by two different antibodies), FGF2 and SLAF1, while FINC, TSP1, MMP2, IL5 and S10AD (negative logFC) were less abundant in plasma of patients with a severe or critical course of the disease. The gene discussed is FN1; the disease is COVID-19.