 Optimal immune resilience, IR, is a trait observed across the age spectrum more common in females and associated with better health outcomes. It is characterized by a balanced immunological state that promotes disease resistance and controls inflammation. This balance is reflected in two distinct peripheral blood metrics. CD8 plus T cells and gene expression signatures tracking longevity associated immunocompetence and mortality associated information. These metrics can be used to measure IR levels and monitor changes over time. Optimal IR is also associated with improved survival during COVID-19 and sepsis and longer life spans. Furthermore, it may be reversible through decreased inflammatory stress. This article was authored by Sunil K. Ahutja, Muthusaravanan Manoran, Grace C. Lee, and others.