Assessing the extent and timing of chemosensory impairments during COVID-19 pandemic

Abstract

Chemosensory impairments have been established as a specific indicator of COVID-19. They affect most patients and may persist long past the resolution of respiratory symptoms, representing an unprecedented medical challenge. Since the SARS-CoV-2 pandemic started, we now know much more about smell, taste, and chemesthesis loss associated with COVID-19. However, the temporal dynamics and characteristics of recovery are still unknown. Here, capitalizing on data from the Global Consortium for Chemosensory Research (GCCR) crowdsourced survey, we assessed chemosensory abilities after the resolution of respiratory symptoms in participants diagnosed with COVID-19 during the first wave of the pandemic in Italy. This analysis led to the identification of two patterns of chemosensory recovery, partial and substantial, which were found to be associated with differential age, degrees of chemosensory loss, and regional patterns. Uncovering the self-reported phenomenology of recovery from smell, taste, and chemesthetic disorders is the first, yet essential step, to provide healthcare professionals with the tools to take purposeful and targeted action to address chemosensory disorders and their severe discomfort.

Figure 1

Loss (during—before ratings; violet) and recovery (after—during ratings; yellow) of smell (A), taste (B), and chemesthesis (C). Violin plots represent the smoothed distribution of data; white diamonds indicate the mean; whiskers indicate maximum and minimum values.

Figure 2

(A) Clusters of participants on chemosensory recovery identified by k-means clustering. The scatterplot shows each participant's loading on Dimension 1 (Dim1) and Dimension 2 (Dim2) of the Principal Component Analysis. Partial = smell, taste, and chemesthesis partial recovery; Substantial = smell, taste, and chemesthesis substantial recovery. (B) Correlations between the three principal components with respect to recovery in smell, taste, and chemesthesis. Gray color indicates a positive correlation, whereas shades of red indicate negative correlations. Darker shades indicate stronger correlations.

Figure 3

Alluvial plot showing the pattern of chemosensory loss and recovery clusters in relation to days between the date of onset and completion of the questionnaire. On the left 3 clusters of chemosensory loss while on the right 2 clusters of chemosensory recovery. The flows between the blocks depict the path from loss to recovery. The different colors of flows represent the different time intervals (in days) between the date of onset and completion of the questionnaire. The width of the flow represents the fraction of participants experiencing the recovery either partial or substantial.

Figure 4

Representation of significant interaction effects of the regression models. Fitted lines of the time from onset and region interaction effects on (A) smell recovery and (B) taste recovery.

Figure 5

Flow diagram presenting the selection of the observations included in the present study.