Gut & MicrobiomeWhy Vaccines Work Less in Older Adults and How to Fix That
As people age, vaccines become less effective due to a cascade of biological changes. This review explains how declining gut bacterial diversity, reduced production of short-chain fatty acids, and overactive mTOR signaling work together to weaken immune responses to vaccines. The result is impaired antibody production and poor immune memory. Crucially, these systems interact in a feedback loop — mTOR dysregulation worsens gut dysbiosis, which in turn drives more inflammation and immune dysfunction. The good news: interventions like mTOR inhibitors (such as rapamycin), probiotics, and dietary changes targeting this gut-mTOR axis show promise for restoring vaccine efficacy in older adults. The authors also call for personalized vaccine strategies based on individual microbiome profiling, pointing toward a precision medicine approach for aging populations.
