BCG for the prevention of food allergy — exploring a new use for an old vaccine
BCG has profound immunomodulatory effects that may reduce the risk of food allergy in children
The prevalence of allergic disease in developed countries has risen dramatically since the mid 20th century and Australia now has the highest documented prevalence of childhood food allergy in the world.1 Theories to explain this rise include changes in the timing of food introduction, epigenetic changes related to environmental factors, and alterations in micronutrient status (particularly of vitamin D). Interactions between the human microbiome, microbial exposures during infancy and the developing immune system are particularly important. According to this model, termed the “hygiene hypothesis” or, more recently, “biome depletion”,2 immune system development may be influenced not only by infections, but also by exposures to animals and antibiotics, and through birth by Caesarean section.
There are currently no interventions to combat the epidemic of food allergy. However, vaccination with live attenuated Mycobacterium bovis, also called bacille Calmette-Guérin (BCG), might offer a strategy to reduce the risk of allergic disease at the population level or in high-risk groups. Administered shortly after birth to protect against tuberculosis, BCG is the oldest vaccine still in routine use (since 1921), and is one of the…