Correspondence Problems With Ascribing Between-Trial Differences in BCG Effectiveness to Sensitization With

analyzed the results of 21 trials of BCG vaccination [1], finding that “latitude and age at vaccination/tuberculin testing strin-gency could explain all of the between-trial heterogeneity. ” They conclude that the “absence of prior M. tuberculosis in-fection or sensitization with environmen-tal mycobacteria is associated with higher efficacy of BCG against pulmonary tuber-culosis and possibly against miliary and meningeal tuberculosis.” The first test of the merit of a hypoth-esis is how well it explains prior observa-tions. If the work of Mangtani et al survives scrutiny, then they will have set