Following consent to participate, children will be assessed for BCG scar and tuberculin reaction at 18-19 months of age. Subsequently, the children will be invited to a clinical examination at one of the health centres. The study will be explained again to the mother, and if she accepts to participate, she will draw a randomisation number deciding whether the child will be revaccinated or not. The BCG vaccine given will be the standard dose of 0.1 ml as recommended by WHO in this age group. In the beginning of the study, a group of 800 revaccinated and not revaccinated children will be followed weekly for two months to monitor morbidity and possible adverse effects of the vaccination. It is not expected that Koch like reactions will be common in this age group. However, should there be too many adverse reactions among children with a positive tuberculin test, only tuberculin negative children will be included in the continuation of the trial.