Impact of the Gut Microbiota on Vaccine Responses

Non-responsiveness or poor responsiveness to vaccines are challenging issues in vaccine development, and efforts have been made to find out the potential reasons for these conditions. Intestinal microbiome plays a key role in regulating and development of immune system and the composition and diversity of microbiota in different individuals on the one hand, and the imbalance of intestinal microbial population (Dysbiosis) on the other hand, could be considered as the most effective factors on the human immune system’s response to vaccines. Herein, we reviewed studies on the relationships between gut microbiome and immune response to vaccines. It is known that higher relative abundance of Actinobacteria and Firmicutes could induce more effective immune response to vaccines. In contrast, higher relative frequencies of Proteobacteria and Bacteroidetes are reported in weak immune response to vaccines. There is a strong interaction between the development of immune system and the composition of microbiota throughout life, therefore, it is important to determine the best times for examinations and using the most accurate methods, including sequencing the entire genome and Next Generation Sequencing (NGS). However, interpretation of the results of these researches depends on study designs, inclusion/exclusion criteria, timing of sampling according to the time of vaccination, and the methods used in each study. These considerations could lead to more reliable results and provide better understanding on the crosstalk between microbiota and immune response to vaccines, which will consequently improve vaccine efficacy.