An abnormal composition of Tfh subsets was also observed in patients with COVID-19, who had an increase in the proportion of CXCR3+CCR6– Tfh1 and CXCR3–CCR6– Tfh2 and a decrease in the level of CXCR3–CCR6+ Tfh17 relative to control group values [59]. Here, CCR6 is linked to COVID-19.