Figure 2.

Intestinal microbiome dysbiosis compromises the effectiveness of vaccine antigens secondary to systemic consequences of a chronic inflammation of the intestinal tract. In chronic intestinal inflammatory states, Tregs can suppress immune responses against antigens and this may limit the efficacy of vaccines when vulnerability signals are not sufficient to elicit vaccine-induced immunity via production of vaccine antigen-specific antibodies. A plausible posit is that probiotics can improve vaccine responses by encouraging the intestinal microbiome to restore eubiosis that restores intestinal immunological homeostasis. This figure was constructed and adapted from relevant published works [18,19,20,45,46,47,48].