ACE2 expression in allergic airway disease may decrease the risk and severity of COVID-19

The coronavirus disease (COVID-19) is caused by Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and presents with respiratory symptoms which can be life threatening in severe cases. At the start of the pandemic, allergy, asthma, and chronic obstructive pulmonary disease (COPD) were considered as risk factors for COVID-19 as they tend to exacerbate during respiratory viral infections. Recent literature has not shown that airway allergic diseases is a high-risk factor or that it increases the severity of COVID-19. This is due to a decrease in Angiotensin-converting enzyme 2 (ACE2) gene expression in the nose and bronchial cells of allergic airway diseases. Conventional asthma treatment includes inhaled corticosteroids (ICS), allergen immunotherapy (AIT), and biologics, and should be continued as they might reduce the risks of asthmatics for coronavirus infection by enhancing antiviral defence and alleviating inflammation.