A Novel Olfactory Self-Test Effectively Screens for COVID-19

Abstract

Key to curtailing the COVID-19 pandemic are wide-scale testing strategies 1,2 . An ideal test is one that would not rely on transporting, distributing, and collecting physical specimens. Given the olfactory impairment associated with COVID-19 3-7 , we developed a novel measure of olfactory perception that relies on smelling household odorants and rating them online. We tested the performance of this real-time tool in 12,020 participants from 134 countries who provided 171,500 perceptual ratings of 60 different household odorants. We observed that olfactory ratings were indicative of COVID-19 status in a country, significantly correlating with national infection rates over time. More importantly, we observed remarkable indicative power at the individual level (90% sensitivity and 80% specificity). Critically, olfactory testing remained highly effective in participants with COVID-19 but without symptoms, and in participants with symptoms but without COVID-19. In this, the current odorant-based olfactory test stands apart from symptom-checkers (including olfactory symptom-checkers) 3 , and even from antigen tests 8 , to potentially provide a first line of screening that can help halt disease progression at the population level.

COVID-19 and anosmia: The story so far

“…33 An online olfactory tool for 12,020 participants from 134 countries indicated that their olfactory ratings were significantly correlated with the national COVID-19 infection rate in their countries over time. 28 Additionally, this real-time online tool showed considerable suggestive power at the individual level, with a sensitivity of 90% and specificity of 80%. 28 There was an independent and significant correlation between the viral clearance rate and the SST scores in COVID-19-induced anosmia patients, with a sensitivity of 79% and specificity of 87% (AUC = .883) for predicting viral clearance when the SST was >10.5.…”

“…28 Additionally, this real-time online tool showed considerable suggestive power at the individual level, with a sensitivity of 90% and specificity of 80%. 28 There was an independent and significant correlation between the viral clearance rate and the SST scores in COVID-19-induced anosmia patients, with a sensitivity of 79% and specificity of 87% (AUC = .883) for predicting viral clearance when the SST was >10.5. 34 Olfactory and gustatory dysfunctions were also associated with the prognosis of COVID-19 and were negatively associated with mortality in patients with an odds ratio of .26 (.15-.44).…”

“…27 In addition, participants can also measure olfactory perception by rating possible household odorants with a realtime online tool. 28 Nowadays, the application of large-scale olfactory tests for COVID-19 is still limited. 29 Some patients with COVID-19induced anosmia self-reported normal olfaction; however, the psychophysical olfactory evaluation revealed mild anosmia.…”

“…27 In addition, participants can also measure olfactory perception by rating possible household odorants with a real-time online tool. 28…”

COVID-19 pandemic: different roles for scientific publications and funding face to epidemiological data—an European, country-based perspective

“…As such, based on the affordability of the different measures to tackle the pandemic, poorer countries, less likely to have the chance to be included in scientifically relevant large consortia, thus not necessarily receving wide amounts of money or not having the possibility to translate such funding into viable research frameworks, should adopt early screening strategies, relying on fast, useful biomarkers for infection detection, in turn being economically affordable. They could span from questionnaires about the quality of life of such people until home-based screening tools for side-effects, that might occur in the asymptomatic population even early during the infection process, therefore blocking the infection chain early [ 6 ].…”