Among patients with COVID-19, an increase in the proportion of Th2 cells in circulation was associated with a poor prognosis, and patients who died had higher levels of CXCR3–CCR6– Th in circulation, while no significant differences were found in the percentage of Th1 or Th17 between the COVID-19 group and control patients [45]. This evidence concerns the gene CCR6 and COVID-19.