Regarding antioxidant enzymes, the activity of SOD (35.03 ± 21.03 vs. 44.77 ± 23.02 U/g Hb × 103, p = 0.280), GSH (83,199.58 ± 8245.14 vs. 85,394 ± 6188.39 U/g Hb × 103, p = 0.434) and CAT (5.28 ± 4.34 vs. 2.35 ± 5.47 U/g Hb × 103, p = 0.036) was statistically lower in patients with COVID-19 compared to healthy controls (Figure 3). This evidence concerns the gene GSTM1 and COVID-19.