Figure 2: Longitudinal comparison of data obtained from the same HCW recently and 5 years prior. GFT-G data obtained 5 years prior were compared with recent results obtained using the QFT-G (A) and the QFT-GIT (B) tests. IFN- levels are plotted on a linear scale and changes in the same subjects are shown by lines. In both assays, an IFN- level less than 0.1 IU/ml was a negative result. IFN- levels falling in the shaded area (0.1 IU/ml ≤ IFN- level <0.35 IU/ml) are regarded as intermediate in Japan.