The magnitude of IFN-γ release in the ESAT-6 free IGRA antigen tubes was comparable to the QFT (Qiagen) in samples from TB cases (median 3.1 IU/ml (IQR 0.6–8.5 IU/ml) vs 3.8 (0.6–9.5 IU/ml), p = 0.161); but significantly lower in the QFT (in-house) tubes (median 3.3 IU/ml (IQR 0.4–8.5 IU/ml, p = 0.041) compared to QFT (Qiagen) (Fig. 2). Here, IFNG is linked to tuberculosis.