Olfactory mucosa transcriptome of COVID-19 hyposmia long-haulers and recovered patients.

SARS-CoV-2 infection may cause olfactory deficits in many patients that persist for few days or may last longer, up to months. In order to understand the differences between long-haulers and recovered patients, the olfactory epithelium transcriptome was studied in 4 groups (N= 5 each): healthy controls (Group 4), and 3 COVID-19 groups: patients without olfactory disturbances (Group 3), with long-lasting olfactory disturbances (Group 1) or with transient olfactory disturbances (Group 2). miRNA expression profile does change in all infected patients, yet without differences among the 3 groups of patients. On the contrary, olfactory mucosa transcriptome by RNA-Seq significantly changes according to the clinical symptoms. Olfactory long-haulers show changes in immune responses mediated by neutrophils and zinc homeostasis, suggesting a role in maintaining long-term olfactory symptoms.