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. 2022 Apr 12;9:852998. doi: 10.3389/fmed.2022.852998

Figure 1.

Figure 1

Schematic mechanism proposal of anosmia/hyposmia in COVID-19. (A) SARS-CoV-2 alpha variant. (1) Infection and destruction of olfactory epithelial supporting cells (olfactory sustentacular cells), resulting in inflammation, and abnormalities in local homeostasis; (2) infection or immune-mediated damage of surrounding cells (vascular cells) resulting in hypoperfusion, inflammatory cell recruitment, cytokine release, and the production of chemical neurotoxins. (B) SARS-CoV-2 Omicron variant. Omicron mechanism of cell entry based on a TMPRS22 dependent and non-dependent manner may involve a more heterogenous tropism with less replication and the consequent minor local inflammation produced. (C) SARS-CoV-2 vaccines may not alter the levels of replicating virus in the olfactory epithelium once viral infection establishes but may instead protect through accelerated clearance or enhanced neutralization of infectious viral particles.