Recruitment: All LBW children delivered at the maternity ward of the national hospital at the local Health Centre will be offered enrolment in the study. Furthermore, all children born at home in the study area will be weighed and referred for BCG vaccination at the health centres as quickly as possible. For mothers of LBW children, the current policy and the purpose of the study will be explained. If she accepts participation, she will draw a randomisation number indicating whether the children will be BCG vaccinated early or not. At the time of enrolment, children will be examined clinically with anthropometrics, and major risk factors will be documented (including TB exposure at home, recent infections, access to malaria drugs, ethnic group, schooling, housing conditions, mother's recent drug consumption). Newborns will only be included in the study if they are considered sufficiently healthy to be discharged from the hospital, or when they arrive at the health centre if born at home. Twins will be a large part of the LBW children as twinning is common in the study area (around 2% of births). They will be allocated to the same group, as there could be confusion for the mother as to who had been vaccinated. As is happening at the moment, mothers of children not receiving vaccination at birth will be recommended to attend a local health centre as soon as the child has gained weight. For ethical reasons, it will not be possible to use a placebo as this could mean that some children would not be BCG vaccinated if the mother believed that the child had in fact been vaccinated. The children who are not vaccinated initially will subsequently be vaccinated at the limited number of health centres in the capital, which administer BCG vaccination. The intradermal vaccination technique and vaccine storage will be supervised, and it will be monitored as to whether scar-formation and PPD reactivity is similar in children vaccinated at the different centres to assure that vaccinations have been administered in the same way.