- All participants must demonstrate a negative QuantiFERON® (QFT) assay result within 52 weeks of transplant regardless of Purified Protein Derivative (PPD) status. Participants with a positive QFT assay will not be eligible for the study unless they have completed treatment for latent TB and have a negative chest x-ray. QFT testing done within 52 weeks before transplant is acceptable as long as there is documentation of the results. Prior recipients of a Bacillus Calmette-Guérin (BCG) vaccination are not exempt.