CD4 and COVID-19: When analyzing the differences in the Th subsets between in COVID-19 patients and controls, it was found that the percentage of CD4+ T lymphocytes with Th1 and Th17 phenotype was significantly reduced in the cells of COVID-19 patients (2.99% vs. 6.68%, p < 0.001 for Th1; and 3.41% vs. 6.95%, p = 0.012 for Th17).