Relationship between odor intensity estimates and COVID-19 population prediction in a Swedish sample

Iravani, B.; Arshamian, A.; Ravia, A.; Mishor, E.; Snitz, K.; Shushan, S.; Roth, Y.; Perl, O.; Honigstein, D.; Weissgross, R.; Karagach, S.; Ernst, G.; Okamoto, M.; Mainen, Z.; Monteleone, E.; Dinnella, C.; Spinelli, S.; Marino-Sanchez, F.; Ferdenzi, C.; Smeets, M.; Touhara, K.; Bensafi, M.; Hummel, T.; Sobel, N.; Lundstrom, J. N.

In response to the COVID-19 pandemic, countries have implemented various strategies to reduce and slow the spread of the disease in the general population. For countries that have implemented restrictions on its population in a step-wise manner, monitoring of COVID-19 prevalence is of importance to guide decision on when to impose new, or when to abolish old, restrictions. We are here determining whether measures of odor intensity in a large sample can serve as one such measure. Online measures of how intense common household odors are perceived and symptoms of COVID-19 were collected from 2440 Swedes. Average odor intensity ratings were then compared to predicted COVID-19 population prevalence over time in the Swedish population and were found to closely track each other (r=-0.83). Moreover, we found that there was a large difference in rated intensity between individuals with and without COVID-19 symptoms and number of symptoms was related to odor intensity ratings. Finally, we found that individuals progressing from reporting no symptoms to subsequently reporting COVID-19 symptoms demonstrated a large drop in olfactory performance. These data suggest that measures of odor intensity, if obtained in a large and representative sample, can be used as an indicator of COVID-19 disease in the general population. Importantly, this simple measure could easily be implemented in countries without widespread access to COVID-19 testing or implemented as a fast early response before wide-spread testing can be facilitated.