This paper introduces three new concepts: epistemic health, epistemic immunity, and epistemic inoculation. Epistemic health is a measure of how well an entity (e.g. person, community, nation) is functioning with regard to various epistemic goods or ideals. It is constituted by many different factors (e.g. possessing true beliefs, being disposed to make reliable inferences), is improved or degraded by many different things (e.g. research funding, social trust), and many different kinds of inquiry are relevant to its study. Epistemic immunity is the robustness with which an entity is resistant to performing certain kinds of epistemic activity, such as questioning certain ideas, believing certain sources, or making certain inferences. Epistemic inoculation occurs when social, political or cultural processes cause an entity to become immune to engaging in certain epistemic activities. After outlining each of these concepts, we close by considering some of the risks associated with attempts to improve others’ epistemic health.