The Booster Effect in Two-Step Tuberculin Testing among Young Adults in Montreal

Abstract

In young adults, booster reactions due to previous tuberculous infection are uncommon and cannot be distinguished from false-positive reactions due to past exposure to other mycobacteria.

High Prevalence of Latent Tuberculosis Infection in Dialysis Patients Using the Interferon-γ Release Assay and Tuberculin Skin Test

“…If an initial TST was negative, a second TST was placed 1 to 3 weeks later to detect a booster response. The booster phenomenon is thought to represent remote TB infection among elderly persons (31,32) in which waning of immunological response with age initially results in a false-negative TST. The first TST reawakens the immune response so that a second TST will become positive.…”

Diagnosis of tuberculosis infection using interferon-γ-based assays

“…Serial TST testing may induce a boosting phenomenon, compromising its interpretation. 10 In a study performed in Barcelona (Spain), 11 prevalence of LTBI in HCWs without a previous positive TST was higher according to T-SPOT.TB (23.1%), and QFT-IT (17.3%) than according to TST (15.4%). Positive IFN-γ tests were associated with age and degree of occupational exposure, but not with BCG vaccination, a finding consistent with previous studies with QFT-G tests.…”

Tuberculosis contact investigation in low prevalence countries: a European consensus

“…Different strains of BCG provide different levels of post-vaccinal allergy [149]. Both time elapsed since vaccination [150,151] and age at vaccination [148,152] influence the extent of cross-reactivity that might be seen in tuberculin skin testing, and reactions may be boosted by repeat testing (C) [153,154]. Thus, the longer the time elapsed since vaccination and the larger the tuberculin reaction size, the higher the probability that the person is infected with M. tuberculosis, yet a discernible influence of BCG on reactivity may be retained for many years [155].…”