We will include 4,800 normal birth weight infants (> 2500 g) infants randomized to 50,000 IU of vitamin A or placebo given simultaneously with BCG vaccine. The study take place in Guinea-Bissau, West Africa. The study area consists of five districts in the capital of Guinea-Bissau. The Bandim Health Project has been working in the study area for almost 25 years, and a demographic surveillance system has been established and functioned for many years.