Early BCG vaccination and development of atopy

Background The increase in atopic diseases may be partly explicable by a decline of certain infectious diseases, dr changes in childhood Vaccination programmes, or both. We investigated whether BCG vaccination against tuberculosis influences the development of atopy. Methods We did a retrospective cohort study of 216 children with atopic heredity, born in Stockholm between 1989 and 1992, who received BCG vaccination when they were younger than 6 months, and 358 age-matched controls who had not been vaccinated. Both groups attended Sachs' Children's Hospital, Stockholm, Sweden, during 1995-96 for assessment of atopic history and clinical signs of atopic disease. All children also underwent skin-prick testing (SPT) and serum was analysed for allergen-specific IgE antibodies. Serum from parents was also analysed for IgE antibodies. Findings 77 (36%) children in the BCG group and 145 (41%) in the control group had a positive history or clinical signs of atopic disease, in the vaccinated group, 26 (12%) children had one or more positive SPT, and 61 (31%) had circulating allergen-specific IgE antibodies, whereas in the control group, the numbers were 35 (10%) and 84 (27%) respectively. Atopy was confirmed by serology in parents of almost two-thirds of the children in each group. Other risk factors for atopic disease were evenly distributed between the two groups. Interpretation early BCG vaccination in children with atopic heredity does not seem to affect the development of atopic disease before school age.