SOURCE: Mancuso JD, Mody RM, Olsen CH, et al. Chest 2017;152:282-294.
A placebo-controlled trial of bacille Calmette-Guerin (BCG) vaccination was performed among Native Americans from Alaska, Arizona, North Dakota, South Dakota, and Wyoming from 1935-1947. Varying opinions appear in the literature about the length of time during which prior BCG vaccination influences reactions to tuberculin skin testing. For instance, the CDC suggests that tuberculin cross-reactivity is unlikely to persist longer than 10 years post-BCG vaccination.
A publication by Mancuso et al offers us a 55-year follow-up of 3,151 subjects who received the BCG vacccines inclusive of up to 55 years post-BCG vaccination. In this population, within the first five years of follow-up, > 60% of BCG recipients registered positive tuberculin testing results. Although this number waned somewhat over time (only 33% were positive after 50 years of follow-up), more than half of BCG vaccines remained tuberculin-positive throughout the initial 44 years of follow-up.
Based on this data, clinicians should consider that the BCG vaccination effect could influence tuberculin testing responsivity for an essentially indefinite period.