Bacille Calmette Guerin Vaccination in Early Childhood and Risk of
Allergic Disease: A Systematic Review and Meta-analysis of data from 13
large scale studies
Abstract
Background and objectives Several large scale cohort studies suggest
that BCG vaccination in early childhood may reduce the risk of allergic
disease, but the consequences remain controversial. The objective of
this study was to investigate the associations between early childhood
BCG vaccination and the risk of developing allergic disease. Methods
Eligible studies published on PubMed, EMBASE and Cochrane Central
Register of Controlled Trials were systematically sourced from inception
to April 2020. Large-scale cohort or cross-sectional studies with 100
participants or more, focusing on the association between BCG vaccine
and allergic disease including eczema, asthma and, rhinitis were
included. An assessment was undertaken by two independent investigators
looking at methods, interventions, outcomes, and study quality. Odds
Ratio (OR) with 95% confidence interval (CI) were calculated. Results
Our study included 13 large-scale studies involving a total of 260,029
participants. Our quantitative analysis found that administering BCG
vaccine in early childhood significantly reduced the risk of developing
asthma (OR 0.74, 95%CI 0.61 to 0.91), but there was no association
between early childhood BCG vaccination and the risk of developing
eczema (OR 0.87, 95%CI 0.68 to 1.11) or rhinitis. (OR 1.03, 95%CI 0.87
to 1.22). The effect of BCG vaccination with asthma was evident
especially in European countries (OR 0.59, 95%CI 0.40 to 0.88) and
American countries (OR 0.90, 95%CI 0.82 to 0.98) Conclusions Use of BCG
vaccination in early childhood may be associated with a reduced risk of
allergic disease, especially in European and American countries.