Standardized Testing Demonstrates Altered Odor Detection Sensitivity and Hedonics in Asymptomatic College Students as SARS-CoV-2 Emerged Locally

Background Anosmia is a recognized symptom of COVID-19, but the relationship of SARS-CoV-2 exposure with olfactory dysfunction remains enigmatic. This report adds unique data from healthy students tested as the virus emerged locally. Methods Psychometrically validated measures assessed odor detection, identification and hedonics in healthy university students. Data from asymptomatic students (N=22), tested as SARS-CoV-2 unknowingly emerged locally, were compared to students tested just prior to local virus transmission (N=25), and our normative sample (N=272) tested over the previous 4 years. Results The exposed cohort demonstrated significantly reduced odor detection sensitivity compared to the students in the prior group (P=.01; d=0.77; CI 0.17, 1.36), with a distribution skewed towards less detection sensitivity (P=.03). Categorically, the exposed group was significantly more likely to have hyposmia (OR=7.7; CI, 3.1, 19.4), particularly the subset assessed in the final week before campus closure (OR=13.6; CI, 3.4, 35.7). The exposed group also rated odors as less unpleasant (P<.001, CLES=0.77, CI, 0.51, 1.56) and showed a similarly skewed distribution (P=.005). The groups had similar odor identification performance. Conclusion Psychometric measures of odor detection sensitivity and hedonics may detect early SARS-CoV-2 exposure in asymptomatic and pre-symptomatic persons with normal odor identification. Viral detection by nasal associated lymphoid tissue is known to trigger systemic immune effects, but its activation may also reduce smell sensitivity and shift perception of the environment towards unpleasant, increasing the social isolation that may mitigate viral infection or transmission. Regular testing of odor detection and hedonics may have value for identifying regional viral exposure.