- A potential subject with a positive interferon-gamma release assay (IGRA) (e.g., QuantiFERON®-TB Gold or T-spot TB® Test) or a positive tuberculin skin test (≤6 months) is eligible if her/his chest X-ray does not show evidence suggestive of active tuberculosis (TB) disease and there are no clinical signs and symptoms of pulmonary and/or extra-pulmonary TB disease. These subjects with a latent TB infection who have not already received a prophylactic TB treatment must agree in advance to complete such a treatment course.