INCLUSION CRITERIA:  Patients with PCR-confirmed COVID-19 Minimal age:18 years Agree to participate in the trial with written informed consent  Moderate or Severe COVID-19 at the time of enrollment  .  A. Definition of moderate disease (according to Siddiqi et al):  Moderate COVID-19 is defined as disease with fever, respiratory symptoms (dry cough, chest distress, or shortness of breath after activities), and pulmonary imaging findings, and at least one of the following findings:  i) Abnormal coagulation parameters:  D-dimer >1 µg/mL (normal <0.5 µg/mL) Prothrombin time (>13.6 second) or International normalized ratio (INR) ≥1.8 Thrombocyte count <100x 10^3/mL  ii) Increased pro-inflammatory markers:  C-reactive protein (CRP) ≥26.9 mg/L Procalcitonin ≥0.5 ng/mL, Lymphocyte count <1.5x 10^9/L) or Neutrophil/Lymphocyte ratio (NLR) >3.3  iii) Presence of risk factors or comorbidities:  Age >65 years Type 1 Diabetes Mellitus or type 2 Diabetes Mellitus (with any of the following: Fasting blood glucose ≥126 mg/dl, 2-h plasma glucose ≥200 mg/dL, or random plasma glucose ≥200 mg/dL, plus HbA1C >6.5%) Chronic kidney disease (creatinine >2.0 mg/dL) or with routine hemodialysis Chronic liver Disease with signs of liver cirrhosis; Child-Turcotte-Pugh (CTP) Class A (score 5-6) or Class B (score 7-9) or higher; or Model for End-Stage Liver Disease (MELD) score <39 Heart failure (New York Health Association [NYHA] Class I or II) Bronchial asthma, chronic obstructive pulmonary disease (COPD), or pulmonary tuberculosis Cancer (particularly patients with chemotherapy or immunotherapy) Immunocompromised conditions, including HIV/AIDS, post-organ transplantation, or judged by attending physician (preferable after specialist consultation) Long-term corticosteroid use autoimmune disease Sequential Organ Failure Assessment [SOFA] score ≥5.65 Body Mass Index (BMI) ≥35 kg/m2  B. Definition of severe COVID-19 (according to Siddiqi et al):  Severe Covid-19 is defined as disease with a respiratory rate ≥30 breaths/min, oxygen saturation <90% or oxygenation index (PaO2/FiO2) ≤300 mmHg, and/or lung infiltrates >50% within 24-48 h.  EXCLUSION CRITERIA:  Pregnant or lactating woman History of transfusion reaction, blood-group incompatibility, IgA deficiency, or Allergy to Immunoglobulin-containing substances Concurrent participation of clinical trials of COVID-19 treatment Possibility of transfer to other hospital within 72 hours Heart Failure (NYHA Class III or higher) or other diseases with risks of volume overload  Permanent organ failure unrelated to COVID-19, including:  End-stage liver disease (CTP score >10 or MELD score >40) End stage renal disease with creatinine clearance <30% or in routine dialysis Multiple organ failure (SOFA score ≥11) Concomitant condition or treatment with risks of thrombosis, e.g., cryoglobulinemia, refractory hypertriglyceridemia, or monoclonal gammopathy