Prior findings in various viral respiratory diseases including SARS-CoV-related pneumonia suggest that convalescent plasma can reduce mortality, although formal proof of efficacy is still lacking. The investigators propose to evaluate intravenous administration of convalescent plasma (CP) obtained from COVID19 survivors in COVID19 patients who are in the medium stage. Supportive data exist for use of convalescent plasma in the treatment of COVID19 and other overwhelming viral illnesses. The study team wants to test the hypothesis that treatment with COVID19 CP will demonstrate salutary effects on COVID19 disease severity/duration, with the primary objective to reduce mortality. In addition, a major secondary objective to reduce the requirement for and/or duration of mechanical ventilation. This phase is to test the safety and efficacy of CP therapy.

Coronaviruses are among the most common causes of the common cold in humans. In recent decades, coronavirus has caused several epidemics worldwide with a vast number of deaths such as severe acute respiratory syndrome-SARS (2003) with 8098 people infected, and 774 people died over 29 countries. The disease caused by SARS CoV-2 (COVID19) is manifest by fever, fatigue, dry cough, pharyngitis, and headache. In addition to the common clinical presentation of respiratory distress, and increasing frequency of cardiovascular manifestations has become evident.

In this context, the investigators propose to evaluate the safety and efficacy of intravenous administration of convalescent plasma (CP) obtained from COVID19 survivors in patients requiring hospitalization for symptomatic "high risk" COVID19 disease. The study team wants to test the hypothesis that treatment with COVID19 CP will demonstrate salutary effects on COVID19 disease severity/duration, with the primary objective to reduce mortality. In addition, a major secondary objective to reduce the requirement for and/or duration of mechanical ventilation. This is a randomized clinical trial comparing convalescent plasma with the standard of care therapy in patients hospitalized for COVID-19 in Vietnam. Patients were randomized 1:1 and received 500 ml of plasma with anti-SARSCoV-2 neutralizing antibody titers of at least 1:80.

Written informed consent will be obtained all eligible subjects prior to participation.

Convalescent plasma will be obtained from male donors, nulliparous females, or female donors negative for HLA antibodies at least 14 days following recovery from COVID-19 infection.

Inclusion Criteria:

• Age 18-75 years
• SARS-CoV-19 PCR positive
• Moderate stage and above
• Time from onset to screening ≤ 21 days, the SARS-CoV-2 test is still positive

Exclusion Criteria:

• Patients with a history of autoimmune disease or IgA deficiency
• Patients with a history of allergy
• Multi-organ/system failure
• Pregnant or breastfeeding at the time of study
• Cancer, history of heart failure, stroke, bronchial asthma
• Multi-organ/system failure with indications for dialysis, severe hypoxia, failure with conventional treatment methods, indications for ECMO.
• The patient is infected with multidrug-resistant bacteria.
• The patient is participating in another study.
• Time from onset to screening> 21 days