Left: Diagram shows the different site-specific strategies that are showing efficacy in animal models and human trials for promoting tissue-resident memory T cell responses and protective immunity in situ. Right: Non-specific strategies that modulate or enhance immunity at specific sites, in the absence of pathogen challenge, and could serve to fortify tissue responses in advance of new pathogens, and also to address specific immune dysregulations that occurs during aging, from malnutrition, and due to environmental toxins.