Early BCG vaccination and development of atopy.

BACKGROUND

The increase in atopic diseases may be partly explicable by a decline of certain infectious diseases, or 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.