What is a two-step TB test, and who needs one?

A two-step tuberculin skin test (TST) is given as two skin tests a week or two apart to establish a reliable baseline for people who'll be screened periodically — like newly hired health care personnel. It catches the 'boosted' reaction that can otherwise be mistaken for a brand-new infection. A single IGRA blood test (QuantiFERON or T-SPOT) can be used instead of the two-step TST.

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Last verified Tuesday, June 30, 2026 · General information for employers and HR teams, not legal advice.