BCG Vaccination: Does It Protect Against TB Infection?

Bacille Calmette-Guérin (BCG) vaccination complicates diagnosis of Mycobacterium tuberculosis (TB) infection. The recently developed ELISpot assay identifies interferon-γ-producing T-cells that respond to unique TB antigens and not to BCG antigens. The ELISpot is more specific for TB infection than tuberculin skin testing (TST). Investigators in Turkey (including some with patent interests in the ELISpot assay) compared these two tests in 979 child household contacts of 414 adults with newly diagnosed TB.

BCG vaccination was confirmed by the presence of an inoculation scar. TST was considered positive at an induration diameter of 10 mm. Thirteen children were diagnosed with active TB (11 had positive TSTs, and 12 had positive ELISpot results…