IFNG and tuberculosis: Contacts with TB disease had significantly higher median IFN-γ levels in both TB1 and TB2 tubes compared to All Others with TBI (1.50 IU/mL vs 0.96 IU/mL, P = 0.003, and 1.88 IU/mL vs 1.06 IU/mL, P < 0.0001, respectively) (Table 2).