While increased expression of CD4, CD25, and FOXP3 was observed in CD patients compared to the control group (p = 0.02, p = 0.03, and p < 0.0001 respectively) and COVID-19 patients group (p < 0.0001 for all of them), their expression levels in COVID-19 patients decreased compared to controls (p < 0.0001, p = 0.01, p = 0.007, respectively). This evidence concerns the gene CD4 and COVID-19.