Inclusion Criteria:  Inclusion criteria of experimental group:  Signed informed consent voluntarily; Age: >18 years old, gender: no restrictions ; Patients with known clinical manifestations of respiratory impairment or new/aggravated respiratory symptoms diagnosed within one week of onset according to the Berlin definition guidelines.  Control group inclusion criteria:  Age ≥18 years old (including 18 years old), male and female; Male weight ≥50 kg, female weight ≥45kg, and body mass index (BMI) between 19 and 26(inclusive), BMI= weight (kg)/ height (㎡); No smoking, alcohol addiction, no history of drug abuse; No diabetes, asthma, copd, chronic renal insufficiency and other basic diseases; No history of major diseases or infectious diseases (including hepatitis B, hepatitis C, HIV, syphilis); Those who have not taken drugs recently.  Exclusion Criteria:  Exclusion criteria of experimental group:  Patients with diabetes, asthma, copd, chronic renal insufficiency, malignant tumors and other basic diseases; severe malnutrition; Pregnant or lactating women; Patients who have been treated with relevant drugs; The researcher judged that he was not suitable to participate in this study.  Exclusion criteria for the control group:  pregnant or lactation women; severe malnutrition; The researcher judged that he was not suitable to participate in this study.