CD4 and infection: Although the present study of T cells is from the phase 1b HVTN 602 trial and is limited to an immunogenicity assessment, our findings revealed unique clusters of both naïve-like and memory CD4+ T cells that will be interrogated in the planned studies to identify the correlates of protection in the C-040-404 prevention of infection trial, as well as in other studies of BCG and recombinant mycobacterial vaccines.