CD4 and COVID-19: Also, severe or critical COVID-19 patients had relatively lower CD3 count (MMD: -380.8 [-515.3, -246.4], I2: 80%), CD4 count (MMD: -204.9 [-302.6, -107.1], I2: 87%) and CD8 count (MMD: -123.6 [-170.6, -76.6] I2: 66%); all differences measured in terms of cells/μl.