CD4 and COVID-19: In COVID-19 progression, lymphocyte levels showed a significant negative correlation (OR: 0.68, 95% CI: 0.51-0.89), but it was not significant in the subsets of CD3+ T cells (OR: 0.97, 95% CI: 0.93-1.02), CD4+ T cells (OR: 0.93, 95% CI: 0.80-1.08), CD8+ T cells (OR: 0.96, 95% CI: 0.92-1.00), B cells (OR: 0.98, 95% CI: 0.92-1.04), or NK cells (OR: 0.80, 95% CI: 0.61-1.04).