An olfactory self-test effectively screens for COVID-19

Abstract

Background Key to curtailing the COVID-19 pandemic are wide-scale screening strategies. An ideal screen is one that would not rely on transporting, distributing, and collecting physical specimens. Given the olfactory impairment associated with COVID-19, we developed a perceptual measure of olfaction that relies on smelling household odorants and rating them online. Methods Each participant was instructed to select 5 household items, and rate their perceived odor pleasantness and intensity using an online visual analogue scale. We used this data to assign an olfactory perceptual fingerprint, a value that reflects the perceived difference between odorants. We tested the performance of this real-time tool in a total of 13,484 participants (462 COVID-19 positive) from 134 countries who provided 178,820 perceptual ratings of 60 different household odorants. Results We observe that olfactory ratings are indicative of COVID-19 status in a country, significantly correlating with national infection rates over time. More importantly, we observe indicative power at the individual level (79% sensitivity and 87% specificity). Critically, this olfactory screen remains effective in participants with COVID-19 but without symptoms, and in participants with symptoms but without COVID-19. Conclusions The current odorant-based olfactory screen adds a component to online symptom-checkers, to potentially provide an added first line of defense that can help fight disease progression at the population level. The data derived from this tool may allow better understanding of the link between COVID-19 and olfaction.

Covid-19 affects taste independently of smell: results from a combined chemosensory home test and online survey from a global cohort (N=10,953)

“…Findings from our study confirm and extend results from previous studies on the utility of assessing ratings of perceived intensity for actual chemosensory stimuli to evaluate chemosensory dysfunction (Iravani et al, 2020; Snitz et al, 2022). For smell, the intensity of household items was reduced by 47% in the COVID-19+ group compared to the presumably healthy NoSymptoms group.…”

Using SCENTinel® to predict SARS-CoV-2 infection: insights from a community sample during dominance of Delta and Omicron variants

“…We also hypothesized that C19+ vs. C19− participants would rate the average odor intensity rating lower, which was supported. Prior studies using self-testing with odor items found in the home (e.g., spices, fragranced products) found odor intensity ratings were predictive of the prevalence of COVID-19 ( 47 , 49 ), highlighting the usefulness of measures of odor intensity to identify smell loss. We also observed that the odor intensity subtest of SCENTinel® was most strongly correlated with active SARS-CoV-2 infection.…”

Persistent olfactory learning deficits during and post-COVID-19 infection

“…Olfactory assessments range from self-administered odor-based identification of household objects ( Snitz et al, 2021 ) or micro encapsulated familiar odorous substances (University of Pennsylvania Smell Identification Test, UPSIT) ( Moein et al, 2020 ), Sniffin’ Sticks Test ( Lechien et al, 2020 ) or Connecticut Chemosensory Clinical Research Center Test (CCCRC Test) ( Vaira et al, 2020 ). Many of these methods lack precise delivery of odors, which can affect the precision and reliability of behavioral readouts while quantifying olfactory fitness at finer scales.…”

“…Studies encompassing the binary yes/no questionnaires, which test the ability to smell easily available odorous objects, visual to analog scale ratings that assess chemosensory abilities and quantitative olfactory detection and discrimination paradigms have indicated olfactory dysfunctions to be one of the strong predictors of COVID-19 ( Bhattacharjee et al, 2020 ; Li et al, 2020 ; Snitz et al, 2021 ; Gerkin et al, 2021 ). Even after the recovery from the infection is achieved, cases of neurocognitive frailty are seen ( Woo et al, 2020 ; Jaywant et al, 2021 ; Burdick and Millett, 2021 ).…”