In our study, we observed similar sPD-1 levels in the control cohort, Group A, and Group C, with lower levels in Groups B and D. When comparing survivors and non-survivors, sPD-1 concentrations were higher in survivors; these unclear results prevent us from considering sPD-1 as a predictive biomarker for severe COVID-19. This evidence concerns the gene HOXD13 and COVID-19.