Inhalation of nicotine from cigarettes has been demonstrated to increase ACE2 expression in human bronchial epithelial cells via α-7-subtype of the nicotine receptors (α7-nAChR), with a similar increase in ACE2 expression measured in patients with COPD (Brake et al., 2020; Leung et al., 2020). This evidence concerns the gene ACE2 and chronic obstructive pulmonary disease.