A collaborative study on behalf of the Global Consortium for Chemosensory Research:
Covid-19 affects taste independently of smell: results from a combined chemosensory home test and online survey from a global cohort
Ha Nguyen, Javier Albayay, Richard Höchenberger, Surabhi Bhutani, Sanne Boesveldt, Niko A. Busch, Ilja Croijmans, Keiland W. Cooper, Jasper H. B. de Groot, Michael C. Farruggia, Alexander W. Fjaeldstad, John E. Hayes, Thomas Hummel, Paule V. Joseph, Tatiana K. Laktionova, Thierry Thomas-Danguin, Maria G. Veldhuizen, Vera V. Voznessenskaya, Valentina Parma, M. Yanina Pepino, Kathrin Ohla
People often confuse smell loss with taste loss, so it is unclear how much gustatory function is reduced in patients self-reporting taste loss. Our pre-registered cross-sectional study design included an online survey in 12 languages with instructions for self-administering chemosensory tests with ten household items. Between June 2020 and March 2021, 10,953 individuals participated. Of these, 3,356 self-reported a positive and 602 a negative COVID-19 diagnosis (COVID+ and COVID-, respectively); 1,267 were awaiting test results (COVID?). The rest reported no respiratory illness and were grouped by symptoms: sudden smell/taste changes (STC, N=4,445), other symptoms excluding smell or taste loss (OthS, N=832), and no symptoms (NoS, N=416). Taste, smell, and oral irritation intensities and self-assessed abilities were rated on visual analog scales. Compared to the NoS group, COVID+ was associated with a 21% reduction in taste (95% Confidence Interval (CI): 15-28%), 47% in smell (95%-CI: 37-56%), and 17% in oral irritation (95%-CI: 10-25%) intensity. In all groups, perceived intensity of smell (r=0.84), taste (r=0.68), and oral irritation (r=0.37) was correlated. Our findings suggest most reports of taste dysfunction with COVID-19 were genuine and not due to misinterpreting smell loss as taste loss (i.e., a classical taste-flavor confusion). Assessing smell and taste intensity of household items is a promising, cost-effective screening tool that complements self-reports and helps to disentangle taste loss from smell loss. However, it does not replace standardized validated psychophysical tests.
Included in this repository are the scripts needed to replicate the analysis. Download or clone this repository to begin working with the code!