ABSTRACT
Background: Covid-19 curve can be flattened by adopting mass screening protocols with aggressive testing and isolating infected populations. The current approach largely depends on RT-PCR/rapid antigen tests that require expert personnel resulting in higher costs and reduced testing frequency. Loss of smell is reported as a major symptom of Covid-19, however, a precise olfactory testing tool to identify Covid-19 patient is still lacking. Methods: To quantitatively check for the loss of smell, we developed an odor strip, COVID-Anosmia checker, spotted with gradients of coffee and lemon grass oil. We validated its efficiency in healthy and COVID-19 positive subjects. A trial screening to identify SARS-CoV-2 infected persons was also carried out to check the sensitivity and specificity of our screening tool. Results: It was observed that COVID positive participants were hyposmic instead of being anosmic when they were subjected to smelling higher odor concentration. Our tool identified 97% of symptomatic and 94% of asymptomatic COVID-19 positive subjects after excluding most confounding factors like concurrent chronic sinusitis. Further, it was possible to reliably predict COVID-19 infection by calculating a loss of smell score with 100% specificity. We coupled this tool with a mobile application, which takes the input response from the user, and can readily categorize the user in the appropriate risk groups. Conclusion: Loss of smell can be used as a reliable marker for screening for Covid-19. Our tool can rapidly quantitate anosmia, hyposmia, parosmia, and can be used as a first-line screening tool to trace out Covid-19 infection effectively.