SCENTinel: A Rapid Smell Test for COVID-19 Surveillance

Smell loss is a predominant symptom of COVID-19, and initial evidence based on self-reports suggests that chemosensory loss is a sensitive predictor of COVID-19 in the general population, more so than fever. However, given the natural lack of awareness of chemosensory changes, self-reports underestimate the true prevalence of smell loss in patients with COVID-19 by 20% compared to an objective test. Therefore, this study examined testing and deploying a rapid and objective measure of smell ability, the SCENTinel test, inspired by the NIH Toolbox Odor Identification Test. SCENTinel was an inexpensive, convenient, and robust smell test for COVID-19 surveillance of the population that quickly and easily assesses three smell loss factors: odor detection, odor intensity, and odor identification. It was designed for practical use in several contexts, including high-density areas such as community medical sites, universities, subacute care facilities, and both industrial and nonindustrial workplaces. The multi-disciplinary team had expertise in understanding taste and smell, developing and validating chemosensory tests, as well as studying the broad symptomatology of COVID-19. This project aimed to a) fine-tune SCENTinel's ability to predict a positive COVID-19 diagnostic test; b) examine marginal smell loss as a sign of the earliest phases of COVID-19, before a positive diagnostic test; and c) assess the test's psychometric validity with test-retest reliability measures and validation against the NIH Toolbox Odor Identification Test. Together, these aims established a standardized protocol for use of SCENTinel as a rapid and objective smell test that can easily be incorporated into onsite COVID-19 testing centers, schools, and workplaces nationwide. Furthermore, it provided key insights into early-onset chemosensory symptoms in relation to a confirmed COVID-19 diagnosis, providing a crucially needed means to contain the spread of COVID-19.