Table 1.

Study inclusion and exclusion criteria according to study groups.

Criteria	COVID-19 Pneumonia	COVID-19 ARDS	Community acquired pneumonia (bacterial origin)	Sepsis induced ARDS	Healthy controls
Inclusion	Positive nasal swap for SARS-CoV-19 virus (SARS-CoV-2-RNA PCR test, RdRP-Gen IP4) with typical symptoms for COVID-19 infection. CURB-65† ≥1 and clinical symptoms like fever, cough and dyspnea.	Positive nasal swap for SARS-CoV-19 virus Radiologic evidence of pulmonary involvement by CT-scan Mechanical ventilation because of ARDS	community acquired pneumonia without recent hospitalization or association with other healthcare facilities such as nursing homes, dialysis centers, and outpatient clinics. CURB-65† ≥1 and clinical symptoms like fever, cough and dyspnea.	Sepsis or septic shock according to Sepsis-3 criteria (16) ARDS according to Berlin criteria (4)	Charlson Comorbidity Index = 0 (17)
Exclusion	No consent given by individuals or next-of-kin
	Age <18
	Pregnancy
	Preexisting chronic infectious disorders (e.g., endocarditis, HIV or hepatitis)
	Current tumor or malignant disorders
	Limited patient’s life expectancy <6 months (independent of e.g., sepsis/SIRS, pneumonia or localized infection)
	Immunosuppression or steroid therapy (e.g., autoimmune disease, transplantation)

^†Confusion, Urea, Respiratory Rate, Blood Pressure and Age (CURB-65) score for pneumonia severity (18).