This could be due to several differences, such as inadequate IgG titer of CP (unknown on some studies), the standard anti-SARS-CoV-2 treatment used for the CP group and the control group was not the same, the PC was used as a single therapy; PC administration was given in late post-infection phases of COVID-19; high age profile, numerous comorbidities, and a different viral load of patients. This evidence concerns the gene CP and COVID-19.