In cases of immune suppression, repeat testing is advised after recovery.54 55 Further, with indeterminate results, TB infection cannot be ruled out with certainty, and the prognosis may be poorer.54 55 The increased response in the Nil tube found in three participants may signify residual IFN-γ due to ongoing infection,58 and TB infection could not be ruled out. This evidence concerns the gene IFNG and infection.