Comparing P50 values and the distribution of HbO2/PO2 in relation to the standard O2-Hb dissociation curve in 100 COVID-19 patients and 100 non-COVID-19 patients, we found no argument to support the hypothesis that SARS-CoV-2 can be responsible for a clinically significant alteration of O2 binding to Hb, neither at baseline nor later in the disease course. The gene discussed is GSTM1; the disease is COVID-19.