Persistent post-COVID-19 smell loss is associated with inflammatory infiltration and altered olfactory epithelial gene expression

We show that humans with lasting PASC olfactory loss harbor cellular and molecular changes in the olfactory epithelium, the peripheral organ for smell. Biopsy analyses using single cell RNA-sequencing, obtained from 6 patients 4-16 months following infection, identified a dysruption of olfactory epithelium homeostasis with infiltration of unique immune cell populations. Single cell 3' RNAseq of olfactory epithelium from 6 adult human patients with lasting olfactory dysfunction post COVID (PASC) (based on psychophysical olfactory assessment, with SIT scores 17-29) using the 10X Genomics Chromium platform and sequenced on Illumina Nextseq 500 compared to previously published control datasets (Oliva et al., 2021) (Durante et al., 2020).