ACE2 and susceptibility to pneumonia measurement: This has relevance for patients with coronavirus disease 2019 (COVID-19), in which the viral spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds and disrupts the functioning of angiotensin-converting enzyme 2 (ACE2) on cell surfaces, leading to the activation of mitogen-activated protein kinases (MAPKs) and production of proinflammatory cytokines (e.g., interferon-gamma, IL-1β, IL-6, and TNF-α) that cause pneumonia or ARDS [40].