BCG has marked immune stimulatory effects in both animal and human studies and observational studies suggest that BCG is associated with a non-specific reduction in mortality in areas with high infant and child mortality. The specific objective of the study is to examine the effect of revaccination for purified protein derivative of tuberculin (PPD) reaction, scar size, morbidity and mortality in a randomised prospective study of revaccination versus no revaccination among children 19 months of age in Guinea-Bissau. The hypothesis is that revaccination with BCG reduces childhood mortality after 19 months of age by 30%.