Pandemics and the English Language: Concepts Critical for Conversing About COVID-19.

We consider the multiple senses of several key terms that are used to discuss the ongoing COVID-19 pandemic and clarify meanings of the corresponding concepts. Topics addressed include: 1) the meaning of immunity to an infectious agent in varying medical and scientific contexts, 2) the scientific factors that influenced the rapid generation and clinical implementation of safe and effective vaccines for COVID-19, 3) the difference between mutational abrogation of reactivity with B- or T-cell antigen receptors (immune escape) versus active interference with host immune mechanisms mediated by gene products encoded within the genome of the infectious agent (immune evasion), 4) the different ways by which the COVID-19 pandemic has "caused" deaths, and 5) briefly, the challenge of precisely defining the term pathogen.