The results showed that the relative expression levels of CD4, CD25, and FOXP3 mRNA were significantly increased in CD patients (mean ± SD: 1.05 ± 0.45, 0.75 ± 0.39, 1.96 ± 0.99, respectively) compared to the control group (mean ± SD: 0.86 ± 0.37, 0.58 ± 0.37, 0.87 ± 0.75, respectively), (p = 0.02, p = 0.03, and p < 0.0001 respectively) and COVID-19 patients’ group (mean ± SD: 0.18 ± 0.25, 0.32 ± 0.33, 0.33 ± 0.27, respectively), (p < 0.0001 for all of them). This evidence concerns the gene CD4 and COVID-19.