However, IFN-γ (and other) cytokine responses to tuberculosis antigens failed to correlate with BCG-mediated protection from tuberculosis in a large clinical trial in South Africa [18] and a vaccine that elicited IFN-γ responses to mycobacterial antigens did not confer protection from tuberculosis in a phase IIb human clinical trial [19]. This evidence concerns the gene IFNG and tuberculosis.