Is the prevalence of wheeze in children altered by neonatal BCG vaccination?

Background: The prevalence of asthma and atopic disease has increased in recent decades, but precise reasons for this increase are unknown. BCG vaccination is thought to be among a group of vaccines capable of manipulating the immune system toward TH1 dominance and therefore reducing the likelihood of atopic disease. Objective: The aim of this study was to determine the influence of neonatal BCG vaccination on the prevalence of wheeze in a large community population of children. Method: In a historical cohort study, a parent-completed questionnaire was used to identify the prevalence of wheeze in BCG-vaccinated and nonvaccinated children in Manchester, England. Results: There were 2414 participants aged between 6 and 11 years. In a univariate analysis neonatal BCG vaccination was associated with a significantly lower prevalence of wheeze (odds ratio, 0.69; 95% CI, 0.55-0.86), and statistical significance was retained when the analysis was adjusted for potential confounders (odds ratio, 0.68; 95% CI, 0.53-0.87). Conclusion: These results demonstrate an association between asthma symptom prevalence and neonatal BCG vaccination, relating to a possible 27% reduction in prevalence, and are therefore of considerable public health importance. Clinical implications: The capacity of neonatal BCG vaccination to reduce the prevalence of respiratory symptoms in children warrants further investigation. © 2007 American Academy of Allergy, Asthma & Immunology.