Since antigen‐specific memory CD4+ T cells with a Th1‐type profile were associated with a reduced M.tb burden in the animal model, an improved bacterial clearance, and less severe pulmonary inflammation in the human clinical trial,39, 40 our data suggested that Rv3615c induced a sustained adaptive immunity with the potential for a rapid response to M.tb challenge and protection against infection. Here, CD4 is linked to infection.