Clarifying Terminology of Signs in COVID-19

The term "sign" has been used to describe various phenomena observed in patients with coronavirus disease 2019 (COVID-19). Discrepancies in the use of this term have been identified when it is used in context with COVID-19. The goals of this review are to provide an overview, describe signs, and clarify misconceptions regarding the use of these terms in COVID-19 patients. PubMed and Medline databases were searched using individual and Medical Subject Headings (MeSH) terms, including coronavirus, COVID-19, and sign, in human studies within the English literature published from inception to December 31, 2020. Studies where the word "sign" was used in a context different from that for COVID-19 (e.g., sentinel sign) were excluded. Three hundred fifty-seven studies were potentially identified and after applying the exclusion criteria and further adjudication, 92 studies constituted the final data set. The majority of signs found in the COVID-19 literature have been applied and aptly described primarily in radiologic diseases of the chest. The term "sign," in other situations, is often misappropriated as it actually represents a physical finding rather than a sign. A total of 27 radiologic signs have been identified on chest computed tomography (CT) or high-resolution CT (HRCT), and 18 cutaneous signs (or findings) have been observed during the physical examination in COVID-19. Signs lack sufficient sensitivity or specificity by themselves; however, in the appropriate clinical setting, they should raise clinical suspicion for this infectious disease.