AVP and susceptibility to pneumonia measurement: Increased plasma concentration of copeptin, which is a biomarker of AVP release, has been found in circulatory and respiratory disturbances, including hypertension, myocardial infarction, heart failure, valvular heart disease, hypovolemia, hypotonia, hypoxemia, severe pneumonia, SARS-CoV-2 infection, pulmonary embolism, and brain trauma [1,14,15,16,17,18].