Abstract
In order for vaccines to be effective within a given population not only do large numbers of people need to be vaccinated, but a large proportion of those vaccinated must develop protective immunity. The mechanisms that lead to a poor immune response to vaccination are complex and poorly understood, but include both genetic and environmental factors. The bacteria that exist throughout the human body, known as the microbiome, play a variety of roles in the development of the immune system. This is particularly true during infancy when the microbiome and the immune response are developing in tandem. Most vaccines are administered in early childhood to prevent outbreaks of devastating childhood diseases. Understanding the impact that the early microbiome plays in response to vaccination will improve our understanding of vaccine efficacy.