Table 14– Recommended cut-off for tuberculin-skin test (TST) positivity in a contact investigation when interferon-γ release assays are not available
Likelihood of infectionTST induration cut-off
Non-BCG-vaccinated or BCG vaccination <12 months of age 153BCG vaccinated >12 months of age 152
High (close contact of smear-positive tuberculosis patient, expected prevalence of infection ≥10%)
 Immune competent≥10 mm 136≥15 mm
 Immunocompromised
  HIVNegative TST does not exclude infection 16, 135Negative TST does not exclude infection 16, 135
  Other conditions with increased risk of developing TB≥5 mm≥5 mm
Low (other contacts of tuberculosis patient and (opportunistic) screening, expected prevalence of infection <10%)
 Immune competent≥15 mm 136TST not recommended 109
 Immunocompromised
  HIVNegative TST does not exclude infectionNegative TST does not exclude infection
  Other conditions with increased risk of developing TB≥10 mm≥10 mm
  • BCG: bacille Calmette–Guérin; TB: tuberculosis. Data taken from 16, 23, 109, 135, 136, 152, 153.