Bacille Calmette-Guérin Vaccinations and Tuberculin Skin Tests

THE CENTERS for Disease Control and the American Thoracic Society recommend tuberculin testing of persons from countries with high rates of tuberculosis.¹Many of these persons have a history of vaccination with bacille Calmette-Guérin (BCG), which makes the interpretation of tuberculin skin tests more difficult. Vaccination with BCG usually leads to the acquisition of tuberculin sensitivity, but the degree of tuberculin sensitivity is highly variable, depending on the vaccine strain used, vaccine dosage, method of vaccine administration, age at vaccination, nutritional status of the vaccine, and factors known to influence the reaction to tuberculin skin tests. The persistence of tuberculin sensitivity during the months and years after BCG vaccination is also highly variable and, in addition to the previously mentioned factors, depends on the frequency of tuberculin testing after vaccination, frequency of repeat vaccinations, exposure to nontuberculosis mycobacteria, and infection withMycobacterium tuberculosis.^2-11 There is no reliable way