Asthma, a Disease Due to a Lack of Bacterial Infections in Childhood.

A randomised single blinded intervention study in high-risk newborns vaccinated at the age of 6 weeks with BCG or placebo. Inclusion: high-risk was defined as either a mother or a father and a sibling with present or past atopic disease. Exclusion: maternal infection in the last week of pregnancy, the use of immunomodulatory drugs or antibiotics during pregnancy (mother), the use of antibiotics directly post-partum (newborn)