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Background: Anosmia-hyposmia and dysgeusia are common symptoms of mild-to-moderate COVID-19 cases. They are usually, but not always, reversible and the cause is unknown. Methodology: Proteonomic similarity searching (BLAST) was used to test whether SARS-CoV-2 has an unusual degree of similarity to human olfactory receptors as compared with other viruses. Results: SARS-CoV-2 displays two orders of magnitude more similarities to human olfactory receptors than does any other upper respiratory virus or rhinovirus and five times as many similarities as cold-causing coronaviruses. Conclusions: It is hypothesized that IgA antibodies produced against SARS-CoV-2 proteins and secreted in saliva and mucus bind to and block human olfactory receptors. These antibodies cause the reversible form of anosmia-hyposmia associated with COVID-19 infection. The mimicry may also, rarely, lead to autoimmune disease against neurons expressing olfactory receptors, in which case oral or nasal steroids may be therapeutic.