Delayed Tuberculin Skin Testing

Key Message

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.