ACE2 and chronic obstructive pulmonary disease: However, it is known that SARS-CoV-2 enters cells via the angiotensin converting enzyme-2 (ACE2) receptor which may be expressed differentially based on age and underlying comorbidities (chronic obstructive pulmonary disease [COPD], smoking, hypertension, diabetes, and coronary artery disease [CAD]),14 and this may have a biologic impact on infection risk following an exposure.