A new employee to your facility is foreign-born and received the bacillus Calmette-Guérin (BCG) vaccine as a child. Their pre-employment assessment for tuberculosis (TB) should include what?

• A. Two-step PPD as any other employee would receive
• B. IGRA testing only
• C. Chest X-ray only
• D. Single-step PPD

Answer: (A)

The key idea is establishing an accurate baseline for latent TB infection in someone who has received BCG vaccination and may have waning tuberculin sensitivity. A two-step PPD screening is used to uncover any booster response and prevent misclassifying a latent infection as negative. If the first PPD is negative, a second test within a short interval is performed; a positive result on the second test indicates a prior TB infection or exposure rather than a recent booster, allowing correct interpretation in future annual testing. This approach helps avoid missing latent TB that could appear negative on a single test due to waning immunity or BCG-related cross-reactivity. Chest X-ray alone cannot detect latent infection, and relying on a single PPD could miss conversions; while IGRA can be more specific in BCG-vaccinated individuals, many facilities use the two-step TST as the standard baseline screening for new hires to ensure consistent long-term monitoring.