Inclusion Criteria:  Subjects over 18 years old and under 80 years old. Positive results by RT-PCR for SARS CoV-2 Clinical picture compatible with respiratory compromise in the form of pneumonia attributed to COVID-19 (Stage 3, 4 or 5 according to the WHO scale), lasting up to 72 hours from the onset of symptoms to their evaluation to be incorporated into the study. Patient with good disposition towards the study and that signs the informed consent.  Exclusion Criteria:  Patients with clinical disease corresponding to mild / asymptomatic forms (Absence of radiological infiltrate and risk factors, with normal auscultation and arterial saturation of oxygen (SatO2) greater than 95%) Patients with clinical disease corresponding to severe forms (Severe pneumonia: presence of severity criteria (ATS / IDSA), one of two major or three minor criteria.) Patients who have received other therapeutic strategies in the framework of an experimental study that make it difficult to evaluate the results obtained, including (but not limited to): convalescent plasma, lopinavir / ritonavir, hydroxychloroquine, and azithromycin. Pregnant or lactating women. Women of childbearing potential not using an effective contraceptive method (withdrawal, intrauterine device, or oral contraceptives). History of severe anaphylactic reaction with the administration of equine plasma. Patients with comorbidities that justify a risk of high mortality from causes independent of SARS-CoV-2 infection (eg, stage IV cancer) Patient who does not consent to participate.