ABSTRACT
Anosmia is common among COVID-19 patients and anosmia assessment is proposed to be useful in the early diagnosis and prognosis of patients. Data on the pathogenesis of anosmia during COVID-19 suggest potential olfactory nerve involvement. Zinc is an essential micronutrient that regulates the immune responses, and zinc deficiency is known to induce anosmia and ageusia. We previously proposed that a drop in nasal zinc level is a normal nasal immune response to acute viral infections, including SARS-CoV-2 infection, and play a role in the pathogenesis of anosmia. The drop in the local zinc level in response to SARS-CoV-2 may lead to lower type 1 interferons and shift toward Th2 immune responses; if prolonged, it may lead to increased viral replication and more severe disease. In people who are at risk for baseline systemic zinc deficiency, such as the elderly and those with chronic diseases such as, chronic lung disease, diabetes, cardiovascular disease, and cancer, SARS-CoV-2 infection-induced drop in nasal zinc level may be more severe and prolonged and lead to an insufficient anti-viral nasal immune response and control the spread of the virus systemically and to the lungs. A better understanding of the clinical implications of baseline systemic zinc deficiency on anosmia and nasal immune responses may allow the development of new treatment strategies to slow down or stop the systemic invasion of SARS-CoV-2.