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December 2, 1983

The BCG Controversy

Author Affiliations

University of Arizona Health Sciences Center Tucson

JAMA. 1983;250(21):2928-2929. doi:10.1001/jama.1983.03340210026014

To the Editor.—  In their rigorous critique of the methodology of the eight large BCG trials, Clemens and colleagues go far in clarifying "The BCG Controversy" (1983;249:2362). Yet, while briefly noting potential nonmethodological sources of efficacy variation, they fail to emphasize that the three high (≥75%) efficacy trials (in England and Chicago and among Western US Indians) were unique in sharing not only unbiased design but a relative absence of nontuberculous mycobacterial sensitivity in their geographic areas. Although early infection with atypical mycobacteria, highly prevalent in all of the "low-efficacy" trial areas, cannot explain negative BCG efficacy, such atypical mycobacteria infections may account for a large proportion of the difference between 0% and 75% to 80% efficacy.1The narrow confidence interval of the three high-efficacy results rectly rectly establishes that BCG can be— and has been—highly effective in these geographic areas and populations. But we should not be left