Although the lack of reliable correlates of protection for TB makes a go/no-go decision for the advancement of TB vaccines difficult, the three multi-antigenic subunit vaccines, already in clinical development (M72/AS01E, H4:IC31, and ID93/GLA-SE), have commonly shown significant induction of Th1-polarised CD4+ T-cell responses characterised by the production of antigen-specific IFN-γ, TNF-α, and IL-228. This evidence concerns the gene CD4 and tuberculosis.