CCR6 and COVID-19: Recently, the frequency of CXCR3+CCR6− cTfh1 and CXCR3–CCR6− cTfh 2 cells was found to be higher in COVID-19 convalescent patients than in healthy donors, whereas the levels of CXCR3–CCR6+ cTfh17 cells in COVID-19 convalescent patients were decreased [63].