Patients with COVID-19+ had lower GPx (p = 0.021) and SOD (p = 0.002) activities and AGEs’ (p = 0.040) concentrations and higher GR activity (p = 0.0007) and GSTpi (p = 0.0001), TBARs (p = 0.010), and END-1 (p = 0.005) and END-2 (p = 0.00001) concentrations compared to those in the control group. The gene discussed is GSR; the disease is COVID-19.