CXCR3 and infection: CXCR3–CCR6+ CD4+ T cells (CCR6+) formed the largest proportion of AIM+CD4+ T cells in both children and adults (Figure 3B); however, AIM+CCR6+ cells were reduced in children compared with adults during the acute phase of infection (spike-specific: P = 0.001; non-spike-specific: P < 0.0001; Figure 3B).