CD4 and COVID-19: In a recent cohort study of COVID-19 patients within six months of recovery, the CXCR5+CD4+cTfh cell frequencies were significantly higher in COVID-19 patients in the long-term clinically recovered (20∼26 weeks) cohort (LCR) than in those in the short-time clinically recovered (4∼9 weeks) cohort (SCR).