IFNG and tuberculosis: We recruited TB patients and their highly exposed contacts who were further categorized based on results from an IFN-γ-release assay (IGRA): (1) IGRA positive (IGRA+) at recruitment (latently TB infected), (2) IGRA negative (IGRA−) at recruitment and 6 months [non-converters (NC)], and (3) IGRA− at recruitment and IGRA+ at 6 months (converters).