All analyses will investigate whether the effect of BCG differs by sex. We will investigate whether the effect differs by scar status of the mother. In addition stratified analysis by age and weight at enrolment will be conducted. Guinea-Bissau has two distinct seasons, a dry season from December to May and a rainy season from June to November. We will assess whether the effect in the dry season (December-May) is stronger than the effect during the rest of the year.