Vol. 2 No. 9 (2022)
Health Technology Reviews

Delayed Tuberculin Skin Testing

Published September 28, 2022

Key Messages

  • With delayed tuberculin skin testing (TST) a single TST is performed to screen for tuberculosis (TB) infection 8 weeks after exposure to a known case of TB.
  • The clinical utility (i.e., clinical benefits and harms of testing) of delayed TST for identifying TB among close contacts with no known risks compared to testing immediately after and at 8 weeks after TB exposure is not known (no evidence was found).
  • It is not known if delayed TST is a cost-effective approach for identifying TB among close contacts with no known risks compared to testing immediately after and at 8 weeks after TB exposure (no evidence was found).
  • One evidence-based guideline developed in Canada does not provide specific recommendations regarding delayed TST in close contacts with no known risks of TB. However, the guideline authors discuss that a single TST at 8 weeks after TB exposure could be a practical option for medium-priority contacts (i.e., those with a lower risk to develop active disease). For high-priority contacts (i.e., those with the most exposure and highest risk to develop active disease), the authors propose testing immediately after exposure and a repeat test 8 weeks later.