ACE2 and COVID-19: Human evidence demonstrates that SARS-CoV-2 can spread throughout the body via the circulation system because of the abundant expression of ACE2 in arterial and venous endothelial cells and arterial smooth muscle cells in many organs.99 The virus may also damage the blood–labyrinth barrier and invade the inner ear structure by infected and activated monocytes due to attack of the vascular system.100 The process of deoxygenation of erythrocytes by the virus also can lead to hypoxia and further damage to the inner ear.101 Hypoxia even may occur in cases with no COVID-19 symptoms.