Could administration of bacille Calmette-Guérin vaccination at birth protect from the development of asthma and allergic diseases in the western world? Has this question been adequately investigated?

Asthma and allergic diseases are disorders with a predominant Th2 immune response and there is some evidence of an inverse correlation between incidence of tuberculosis and prevalence of allergic diseases. Skewing the immune response towards a Th1 phenotype has been shown to suppress allergic inflammation. One of the ways this could be achieved is by administration of BCG vaccination early in life. Unfortunately, studies examining the protective role of BCG vaccination early in life against development of allergic diseases have shown some conflicting results and this article critically discusses the pitfalls in the currently available data. We propose that well controlled double blind placebo-controlled multi-centre study is carried out to address this important question and if this study shows a favourable outcome simple measures such as offering BCG vaccination early in life could help reduce prevalence of allergic diseases.