Herd Immunity: History, Concepts, and Ethical Rationale.

Public health emergencies are fraught by epistemic uncertainty, which raises policy issues of how to handle that uncertainty and devise sustainable public health responses. Among such responses, a herd immunity policy might be an option. Particularly before the development of vaccines, the current COVID-19 pandemic has highlighted the polarized nature of the political debate concerning the ethical feasibility of herd immunity strategies. This article provides a conceptual framework tailored to uncover the ethical rationale behind such strategies. Clarity on this issue is important in order to facilitate the terms of the political debate when tackling future health emergencies.