The COVID-19 pandemic has been spreading continuously, and in Brazil, until May 31, 2020, there have been more than 450.000 cases with more than 28.000 deaths, with daily increases. The present study proposes to evaluate the efficacy and safety of convalescent plasma in treatment of severe cases of COVID-19 in a multicenter, randomized, open-label and controlled study

Eligible patients will be randomized 1:1:1 into 3 treatment groups: A- standard (control); B- standard and convalescent plasma in a volume of 200ml (150-300ml); C- standard and convalescent plasma in a volume of 400ml (300-600ml). The Bayesian multi-arm and multi-stage model will be used, which will allow an interim analysis after the inclusion of 30 patients, with repeated interim analyses for every 30 additional patients. With this, we expect to define not only the efficacy of convalescent plasma, but also the volume of plasma needed if efficacy is proven. The study will be interrupted if the efficacy of the convalescent plasma group is proven, so that all severely ill patients as defined in the study can receive the convalescent plasma treatment. The same will occur if there is no difference in primary outcome with the use of convalescent plasma or serious adverse effects.

Inclusion Criteria:

• Age = or > than 18 years; .
• Laboratory-proven COVID-19 infection by RT-PCR in any clinical sample . Time since symptom onset less than 10 days at the time of screening; - . Presence of COVID-19 pneumonia, with a typical, indeterminate or atypical compatible image in a chest tomography exam (see definition below) -
• Presence of one of the following criteria:
• Need for> 3L of O2 in the catheter / mask or> 25% in the Venturi mask to maintain O2 saturation> 92% B presence of respiratory distress syndrome with PaO2 / FiO2 <300mmHg If intubated, within 48 hours of orotracheal intubation
• Absence of a history of serious adverse reactions to transfusion, for example, anaphylaxis; - .Participation approval by the research clinician

Exclusion Criteria:

• Already enrolled in another clinical trial evaluating antiviral or immunobiological therapy for the treatment of COVID-19.
• IgA deficiency
• Presence of a clinical condition that does not allow infusion of 400 ml of volume at clinical discretion
• Pregnancy or breastfeeding
• Receipt of immunoglobulin in the last 30 days
• Presence of significant risk of death within the next 48 hours at clinical discretion.