<prompt> Answer this question truthfullyHow does the number of false positives from BCG vaccination compare between Interferon-γ release assay IGRA and PPD testing?  <response>: <reason> Interferon-γ release assay IGRA has fewer false positives from BCG vaccination than PPD testing. BCG Bacillus Calmette-Guérin is a vaccine that is used to prevent tuberculosis TB, but it can also cause a positive reaction in TB skin tests like the PPD purified protein derivative test. The IGRA test is a blood test that measures the immune response to TB-specific antigens, and it is less likely to produce false positive results from BCG vaccination than the PPD test. This is because the IGRA test is more specific to TB and less likely to be affected by cross-reactivity with other types of mycobacteria, which can cause false positives in the PPD test. 