Circulating antigen‐specific CD4 memory T‐cells can participate in protective immune responses either acting as reinforcements to Trm cells32 or protecting tissues not challenged in the initial infection or vaccination.14, 52 Immune protection by circulating memory CD4 T‐cells is delayed compared with Trm‐mediated protection as they must be first recruited to the site of infection and reactivated by local APCs. Here, CD4 is linked to infection.