CD4 and COVID-19: We determined the AUC values for all immune parameters—leucocytes/nL, lymphocytes/nL, CD3+ %, CD3+ cells/μL, CD19+ %, CD19+ cells/μL, CD4+ %, CD4+ cells/μL, CD8+ %, CD8+ cells/μL, NK %, NK cells/μL, IRI, PD-1 CD4+ %, PD-1 CD8+ %, TIM-3 CD4+ %, and TIM-3 CD8+ %—and achieved approximately 70% sensitivity and 70% specificity with an AUC value of 0.729 for predicting COVID-19 mortality.