Bacille Calmette-Guérin Vaccination is Associated with Lower Prevalence of Allergic Diseases in Indian Children

Abstract

Immunization with bacille Calmette-Guérin (BCG) has been shown to augment T helper (Th) 1 biased response and hence gives protection against developing allergies. However, results across the studies have been inconclusive and there is no Indian study verifying this association. We explored the link between BCG vaccination and prevalence of allergic diseases among school children of Chandigarh, North India. In a large cross-sectional study, children aged 7-14 years, with and without documentation and/or scar consistent with BCG vaccination, were examined over a period of 2 years and 5 months with the help of a questionnaire-based survey followed by skin-prick test (SPT). A total of 10,028 children were included. The mean age was 11.04 ± 2.8 years and M/F ratio was 1.1:1. Among them, 77.7% had documentation of BCG vaccination, 17% had a BCG-like scar but no documentation and 5.3% had no scar/documentation. SPT was performed on 1614 (16%) children. In the BCG group (vaccination and/or scar) 16.7% were atopic (positive SPT) compared with 21.3% in no BCG (no vaccination/scar). The prevalence of allergic diseases among BCG(+) subjects was 10.1%. Among these, asthma was the commonest one (6.1%), followed by rhinitis (3.5%) and eczema (0.5%). There was significant negative correlation between BCG positivity, atopy (p = 0.037), and allergic diseases as a whole (p = 0.028), but on independent analysis the negative correlation was strongest with allergic rhinitis (p = 0.011). BCG vaccination is associated with lower prevalence of allergic disorders in Indian children.