Gut Microbiome and the Immune System: Role in Vaccine Response

A vaccine works by allowing the immune system to “practice” on a weakened or killed version of the pathogen or components thereof, including surface proteins, polysaccharides, or toxins. While age is one very important driver of vaccine efficacy, other factors should be considered, including demographics, comorbidities, previous vaccinations, and medication use, but also the intestinal microbiome. This chapter describes how the gut microbiome has both local and systemic impacts on the immune response, and how these can be used to improve vaccine efficacy. Animal models are usually used so that direct causality can be inferred between the composition of the microbiota to a given treatment and/or infection. The latest research in the human microbiome field has made evident that the gut microbiome can impact vaccine responses, from vaccine efficacy to its effect on extending immune memory against a specific pathogen.