Abstract
A symbiotic relationship between humans and the microbiota is critical for the maintenance of our health, including development of the immune system, enhancement of the epithelial barrier, and acquisition of nutrients. Recent research has shown that the microbiota impacts immune cell development and differentiation. These findings suggest that the microbiota may also influence adjuvant and vaccine efficacy. Indeed, several factors such as malnutrition and poor sanitation, which affect gut microbiota composition, impair the efficacy of vaccines. Although there is little evidence that microbiota alters vaccine efficacy, further understanding of human immune system-microbiota interactions may lead to the effective development of adjuvants and vaccines for the treatment of diseases.