CD4 and COVID-19: Marked lymphopenia (median = 653 cells/μL) affecting all lymphocyte subsets (e.g., median CD4 + T lymphocytes = 298 cells/μL, with CD4/CD8 ratio in normal range) [10, 11] and moderately decreased mHLA-DR (median = 11,125 AB/C, control values > 13,500 AB/C) [22] were also hallmarks of initial critically ill COVID-19 patients’ immune profile.