CD8A and tuberculosis: Our study in a population of 19,397 contacts screened with the QFT-Plus at the Singapore TB Contact Clinic showed that those with TB disease and Stringent QFT-Plus Converters (i.e., those highly likely to have recent infection) were significantly more likely to demonstrate CD8+ responses as indicated by TB2-TB1 IFN-γ >0.6 IU/mL, as compared to All Others with TBI.