CD4 and COVID-19: In conclusion, compared to nonsevere COVID-19, severe or critical COVID-19 is associated with increased markers of the innate immune response such as neutrophil count, NLR, IL-6, CRP, and serum ferritin; decreased markers of the adaptive immune response such as lymphocyte, CD4 and CD8 counts; and increased markers of tissue damage and major organ failure including D-dimer LDH, Troponin I, CK-MB, AST, ALT, urea, and creatinine.