"Alar's" eagle eyes found this in the
updated CDC guidelines;
If persons at low risk for both infection and progression are to be tested, selection of the test with the greatest specificity will minimize false-positive results, reduce unnecessary evaluation and treatment, and minimize the potential for adverse events from unnecessary treatment.
This is what the CDC had to say about specificity
In tested populations of persons unlikely to have M. tuberculosis infection, pooled QFT-GIT specificity was 99% and pooled TST specificity from these cohorts, when available, was 85%. Pooled T-Spot specificity was 88% and pooled TST specificity from these cohorts, when available, was 86%.
