Vitamin A supplementation and BCG vaccination at birth may affect atopy in childhood: long-term follow-up of a randomized controlled trial

BackgroundRecent evidence suggests that immunogenic interventions such as vaccines and micronutrients may affect atopic sensitization and atopic disease. We aimed to determine whether neonatal BCG vaccination, vitamin A supplementation and other vaccinations affect atopy in childhood. MethodsIn Guinea-Bissau, low-birthweight infants were randomized to early (intervention) or delayed (usual policy) BCG. A subgroup was also randomly assigned vitamin A supplementation or placebo in a two-by-two factorial design. Participants were followed up at age 3-9years. The main outcome was atopy defined as skin prick test reaction 3mm. Secondary outcomes were symptoms of eczema, asthma and food allergy. ResultsTwo hundred eighty-one children had valid skin prick tests performed, and 14% (39/281) were atopic. There was no significant difference in atopy between the early and delayed BCG groups (OR, 0.71; 95% CI, 0.34-1.47). Atopy was significantly reduced in children who had responded to BCG with a scar (OR, 0.42; 0.19-0.94). Vitamin A supplementation was associated with increased atopy (OR, 2.88; 1.26-6.58), especially in those who received simultaneous BCG (5.99; 1.99-18.1, P=0.09 for interaction between vitamin A supplementation and BCG). Early vs delayed BCG was not associated with symptoms of atopic disease, but vitamin A supplementation increased odds of wheeze within the past 12months (OR, 2.45; 1.20-4.96). ConclusionsThere were no statistically significant effects of early vs delayed BCG on atopy or symptoms of atopic disease. Having a BCG scar was associated with reduced atopy, whereas neonatal vitamin A supplementation was associated with increased atopy. Study RegistrationClinicaltrials.gov NCT 01420705.