Smoking is known to increase the risk for several comorbidities, including diabetes,28 cardiovascular disease,29 and chronic obstructive pulmonary disease (COPD),30 all of which appear to play an important role in the pathology of COVID-19 in humans.31-33 Furthermore, smoking increases expression of Angiotensin-converting enzyme 2 (ACE2), a receptor with high affinity for SARS-CoV-2 binding.34,35 Previous data suggest that tobacco influences the risk of transmission and severity of COVID-19. Here, ACE2 is linked to COVID-19.