CXCR3 and COVID-19: The results showed that CXCR3− TFH cells were more efficient than CXCR3+ TFH cells in supporting memory B cell differentiation into total ASCs in healthy controls, convalescents, and vaccinees (Fig. 7i-k, left panel), which is consistent with a previous report that circulating human CXCR3− TFH cells are more efficient than CXCR3+ TFH cells in supporting B cell differentiation.29 However, CXCR3+ TFH cells showed superior capacity to CXCR3− TFH cells in supporting spike-specific ASCs differentiation in both COVID-19 convalescents and vaccinees (Fig. 7j, k, middle panel).