CD8A and viral infectious disease: Finally, we could detect CXCR5+PD‐1+ CD8 T cells in antigen‐specific T‐cell populations toward chronic viral infections (EBV), but not an acute viral infection (FLU), indicating that chronic antigen stimulation could be required for CXCR5+PD‐1+ CD8 T cells to develop, as is the case in mice [7, 8, 9, 10].