Coronavirus Disease 2019 and Nasal Conditions: A Review of Current Evidence

Abstract

The nasal epithelium expressing enriched angiotensin-converting enzyme II (ACE2), the key cell entry receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), could serve as the first barrier to protect the airway from viral infection. Recent studies have demonstrated that higher viral loads were detected in the nasal cavity than the pharynx in coronavirus disease 2019 (COVID-19) patients, and otolaryngologists should carefully consider infection prevention in clinical practice for the treatment of nasal conditions. Moreover, several studies have indicated that anosmia is one of the clinical characteristics of COVID-19, but the precise prevalence and mechanism remain unclear. Thus far, comorbidity of allergic rhinitis and chronic rhinosinusitis do not seem to be a major risk factor for severe COVID-19. However, we should develop strategies in clinical practice for treatment of nasal diseases during the pandemic. In this article, we reviewed current evidence of the relationship between COVID-19 and nasal conditions, such as COVID-19-related olfactory dysfunction, allergic rhinitis, and chronic rhinosinusitis.

Keywords: ACE2; COVID-19; SARS-CoV-2; olfactory dysfunction; review; rhinitis.

Figure 1. Expression of angiotensin-converting enzyme II (ACE2) receptor in human airway epithelium and role of ACE2. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to ACE2 expressed as receptor on human airway epithelial cells, and the serine protease transmembrane serine protease serine 2 (TMPRSS2) cleaves and activates the spike protein to allow virus-cell fusion and cell entry. ACE2 also has a protective effect on airway tissue by inactivating Ang II and producing Ang 1-7. The expression of ACE2 is modulated by various factors, such as interferons (IFNs), viral infection, smoking, and type 2 inflammation.

Figure 2. Common symptoms of COVID-19, influenza, and allergic rhinitis and their relationships to each other COVID-19, influenza, and allergic rhinitis share many common symptoms.