Probiotics and Vaccination in Children

Immunisation is one of the most beneficial and cost-effective disease prevention measures. However several immunisations are associated with suboptimal seroconversion rates and so the protective effect is not optimal. In the last two decades the concept about the use of probiotic bacteria as novel mucosal adjuvants has engendered a lot of interest due to our increased immunological understanding and the availability of various techniques to enhance existing vaccine specific-immune responses. Mostly in developing countries, many people still die every year from vaccine-preventable diseases such as pneumonia and diarrhea. To date, emphasis has been placed on identifying novel vaccine antigens and adjuvants that induce stronger protective immune responses, as well as developing mucosally-administered vaccines. We would have enormous benefits in allowing safe administration of vaccines in remote areas and we may overcome the necessity for multiple doses. The precise mechanism of action of probiotics is not fully understood, but several animal and human studies have proven immunomodulatory effects involving both the humoral and cellular components of the host's immune system. This review discusses whether dietary supplementation with oral probiotics enhances the immune response of infants after routine vaccinations and also evaluates clinical effects of probiotics in adults. Further well designed, randomized, placebo-controlled studies are needed to understand fully the immunomodulatory properties of probiotics, whether the effects exerted are strain and age-dependent, and their clinical relevance in enhancing protection following vaccination