Hb–O2 cooperativity was not significantly different between the healthy controls or COVID-19 subjects (pH 7.2: 2.68 ± 0.20 vs 2.57 ± 0.11, p = 0.1433; pH 7.4: 2.65 ± 0.21 vs 2.56 ± 0.12, p = 0.1826; and pH 7.6: 2.66 ± 0.28 vs 2.51 ± 0.14, p = 0.0968, healthy control vs COVID-19, respectively; Figure 5B). This evidence concerns the gene GSTM1 and COVID-19.