CCR4 and COVID-19: The minimum level of Th17 was observed in patients with severe COVID-19, moreover, within the framework of the general pool of CCR6+ Th17, it was exactly noted in severe patients that there was a decrease in the proportion of CCR4− CXCR3+ Th17.1 cells and an increase in CCR4+ CXCR3—“classical” Th17 [89].