BACKGROUND: Vaccination with Bacillus Calmette-Guérin (BCG) is used in many countries as protection against tuberculosis. Studies have suggested that BCG may also have non-specific effects, reducing non-tuberculosis mortality, morbidity, and atopic manifestations. In this study, we evaluated the effect of neonatal BCG vaccination on allergic sensitization and suspected food allergy at 13 months of age.

METHODS: The Danish Calmette Study was conducted from 2012 to 2015 at three Danish hospitals. Within 7 days of birth, the 4262 newborns of 4184 included mothers were randomized 1:1 to BCG or to a no-intervention control group. Exclusion criteria were gestational age <32 weeks, birth weight <1000 g, known immunodeficiency, or no Danish-speaking parent. Follow-up information was collected through telephone interviews at 3 and 13 months of age. Subgroups of participants were offered blood sampling at 13 months of age.

RESULTS: By 13 months of age, the parents and/or general practitioners of 5.6% (117/2089) of the children in the BCG group and 6.1% (126/2061) of the control group suspected food allergy, resulting in a risk ratio comparing BCG-vaccinated children with control children of 0.91 (95% CI 0.71-1.16). Among 1370 blood samples, sensitization (Phadiatop Infant >0.35 kUA/L) was found in 55 of 743 (7.4%) children in the BCG group and 50 of 627 (8.0%) of the control group (risk ratio 0.94 [0.65-1.36]).

CONCLUSION: In this randomized clinical trial, neonatal BCG had no significant effect on suspected food allergy or on sensitization at 13 months of age.