CD4 and COVID-19: A previous study demonstrated a significant association between low levels of CD8+ T cell (< 201 cells/μl) and an increased risk of composite outcome; additionally, low levels of CD4+ T cell (< 368 cells/μl) and CD8+ T cell (< 201 cells/μl) were closely associated with the mortality outcome in COVID‐19 patients receiving Nirmatrelvir therapy (24).