BACKGROUND: Studies have suggested that Bacillus Calmette-Guérin (BCG) vaccination may reduce the risk of allergic diseases, including atopic dermatitis.

METHODS: The Danish Calmette Study was conducted 2012-2015. Within 7 days of birth new-borns were randomised 1:1 to BCG or no BCG. Exclusion criteria were gestational age <32 weeks, birth weight <1000 g, known immunodeficiency or no Danish-speaking parent. Data were collected through telephone interviews and clinical examinations until 13 months.

RESULTS: Clinical atopic dermatitis was diagnosed in 466/2,052 (22.7%) children in the BCG group and 495/1,952 (25.4%) children in the control group (RR = 0.90 [95% confidence intervals 0.80-1.00]). The effect of neonatal BCG vaccination differed significantly between children with atopic predisposition (RR 0.84 (0.74-0.95)) and children without atopic predisposition (RR 1.09 [0.88-1.37]) (test of no interaction, P = .04).

CONCLUSION: Among children with atopic predisposition, the number-needed-to-treat with BCG to prevent one case of atopic dermatitis was 21 (12-76).