18^th International Virology Summit

Vaccines and the Microbiome

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. A higher relative abundance of the phylum Actinobacteria (oral and parenteral vaccines) and Firmicutes (oral vaccines) was associated with both higher humoral and higher cellular vaccine responses, while a higher relative abundance of the phylum Proteobacteria (oral and parenteral vaccines) and Bacteroidetes (oral vaccines) was associated with lower responses. Subjects whose intestinal microbiota is dominated by Bifidobacterium demonstrated a broader level of adaptive immune response to vaccinations. On the other hand, infants with higher ratios of Enterobacteriales, Pseudomonadales, and Clostridiales in their intestinal microbiota exhibited lower immune response to vaccination.