Atopic disorders among Estonian schoolchildren in relation to tuberculin reactivity and the age at BCG vaccination

Background: Published data about a relationship of atopic diseases to Bacillus Calmette‐Guérin (BCG) vaccination and tuberculin responses are inconsistent. Our aim was to determine this association in a country with a low prevalence of allergies. Methods: A random sample of 10–11‐year‐old schoolchildren in Tallinn was studied by a parental questionnaire (n = 979) and skin‐prick tests (n = 643), according to the International Study of Asthma and Allergies in Childhood. Data about BCG vaccinations and tuberculin tests were obtained from school records (n = 723). Results: The prevalence of allergic symptoms and atopy was similar in children vaccinated during the first month of life and later. Positive tuberculin responses (≥5 mm) were inversely related to symptoms of asthma [odds ratio (OR) 0.10 (95% confidence interval 0.00–0.68) for exercise‐induced wheezing; OR 0.37 (0.12–0.99) for night cough], and eczema [OR 0.53 (0.28–0.98)] but not to atopy. However, among BCG‐revaccinated children, atopy tended to be more common in tuberculin responders, and the atopic children were significantly more likely to have a positive tuberculin response after the revaccination than would be predicted by their first test. Conclusions: We found no protective effect of early BCG vaccination against atopy in school age, although tuberculin responses and allergic symptoms were inversely related.