The URT is not only the entry portal of the airways but also contains the highest percentage of ACE2-expressing respiratory epithelial cells across all the airways.3,4 In contrast to NCS, ICS are largely deposited in the more distal and lower airways, which are anatomical regions important in the severity of COVID-19 (an outcome for which ICS have demonstrated success in some but not all clinical trials28,35,36) but are likely less relevant for establishing SARS-CoV-2 infection.1,4,37,38. Here, ACE2 is linked to COVID-19.