Clinical Trial for Assessment of Anti-SARS-CoV-2 Serum for Early Treatment of COVID-19 Cases

Inclusion Criteria: 1. Adults 18 years of age or older; 2. Diagnosis of SARS-CoV-2 infection confirmed by RT-PCR or antigen test no more than 5 days ago; 3. Onset of clinical signs and symptoms of COVID-19 no more than 5 days manifested as: 1. Presenting sudden onset of anosmia and/or ageusia without any other reasonable explanation and/or; 2. Thoracic image by radiography, tomography or ultrasonography compatible with acute clinical symptoms findings of COVID-19 and/or; 3. Acute onset of cough accompanied by fever and/or 4. Acute onset of three or more of the following symptoms: fever, cough, fatigue or general weakness, headache, myalgia, sore throat, runny nose, dyspnea, anorexia or nausea or vomit, diarrhea and mental status change. 4. Oxygen saturation by pulse oximetry ≥92% 5. Agree to periodic contacts by phone, electronic means and home visits; 6. Demonstrate intention to participate in the study, documented by Informed Consent Form signature on the part of the participant. For the very high risk group: 7. Being on continuous drug immunosuppressant more than two weeks due to a basic medical condition (e.g. transplant or cancer); For the high risk group: 8. To present at least two risk factors for developing serious COVID-19 (Over 60 years of age; diabetes mellitus; chronic obstructive pulmonary disease; kidney disease; cardiovascular diseases and body mass index ≥ 35). Exclusion Criteria: 1. Presenting COVID-9 in need of oxygen therapy on the moment of study inclusion, in other words, score 5 or higher in WHO COVID-19 progression scale; 2. Behavioral, cognitive or psychiatric disease that, in principal investigator opinion or his/her medical representative, affect the participant capacity in understanding and collaborating with study protocol requirements; 3. Any use considered alcohol or drugs abuse in the last 12 months prior to study inclusion that caused medical, professional or family problems, as indicated by clinical history; 4. Severe allergic reaction history or anaphylaxis to heterologous serum or product components of the study; 5. To have received heterologous serum or convalescent plasma in the last three months before of study inclusion, or planned administration of hemoderivatives or immunoglobulin on the next 28 days of study inclusion; 6. The participant is a team member who is conducting the study or is in a dependent relationship with one of the study team members. Dependency relationships include close relatives (in other words, sons, partner/spouse, brothers, parents), as well as Researcher staff or staff from the location conducting the study; 7. Any other condition that, in the principal investigator opinion or his/her medical representative, could threaten the safety or rights of a potential participant or which prevents him from fulfilling with this protocol. For female: 8. Pregnancy (confirmed by positive β-hCG test), breastfeeding and/or expressing an intention to have sexual practices with reproductive potential without using a contraceptive method within four weeks of the product administration; For stages A and B: 9. Previous immunization with vaccine against COVID-19