NOS3 and COVID-19: Among the alleles of the endothelial nitric oxide synthase (NOS3) gene dpSNP, rs2070744, in patients with COVID-19 in both the study and control groups, the wild T-allele dominated over the C-allele as follows: in the study group by 19.44% (χ2 = 10.89; p = 0.001), and in the control group by 18.75% (χ2 = 6.75; p = 0.009).