CD4 and tuberculosis: Our results and algorithm validates previous study cohorts, predicting a higher risk of active TB in those with low CD4 cell counts and high HIV viral loads (2/309, 0.7%), and in those with high CD4 cell counts and low HIV viral loads, only when IGRA was positive (2/72, 2.8% and 1/45, 2.2% in cohort 1 and 2, respectively).