Plasma from convalescent individuals (convalescent plasma, CP) has been used for more than a hundred years for the treatment of infectious diseases. Among patients with COVID-19, it has been used first, in patients with severe infection. Although it is a safe treatment, it has not been possible to demonstrate a reduction in mortality in cases of acute respiratory distress syndrome.

The objective of the clinical trial is to evaluate the efficacy and safety of the early use (less than 5 days of symptoms) of CP in patients infected with SARS-CoV-2 with risk factors for severe disease.

The primary efficacy endpoint was the proportion of patients requiring oxygen therapy to maintain saturation >93% on day 14. Secondary objectives included, evaluation of the safety of the treatment, measured as the appearance of some adverse event related to the CP infusion; the evolution of COVID-19 symptoms and WHO progression scale status at day 14 and 28 after inclusion; the need for hospitalization due to progression of COVID-19. COVID-19 progression was considered as worsening of respiratory symptoms requiring oxygen therapy at some point. Finally, death from any cause was evaluated at 28 days, after inclusion in the study.

Inclusion Criteria:

Patients with SARS-CoV-2 infection, confirmed by any validated microbiological technique, and with one or more symptoms associated with COVID-19 with ≤5 days of evolution and with an oxygen saturation ≥93% breathing room air.

In addition, the patients had to present some risk factor for severe disease:

• Chronic heart failure (NYHA ≥ 2)
• Arterial hypertension under pharmacological treatment
• Chronic lung disease: COPD (bronchitis, emphysema or chronic obstruction) with dyspnoea at least on moderate exertion, or moderate-severe asthma (that required inhaled corticosteroids to control symptoms or had received systemic corticosteroids during the last year due to decompensation)
• Chronic renal failure (glomerular filtration rate <60 ml/min/1.73 m², by CKD- ILD)
• Diabetes mellitus requiring pharmacological treatment or obesity grade ≥ I (BMI ≥30 Kg/m2).
• Patients ≥65 years were included, regardless of other risk factors.

Exclusion Criteria:

• Duration of symptoms >5 days
• Dyspnoea at rest
• Need for supplemental oxygen to maintain O2 saturation >93%
• Solid neoplastic or haematologic disease (except skin cancer) with active treatment in the last 3 months before the onset of symptoms
• Patients under chronic corticosteroid treatment (equivalent to prednisone 10 mg/d for at least 28 days) or immunosuppressive treatment
• Decompensated liver cirrhosis
• Participation in another clinical trial
• History of hypersensitivity to haematological derivatives
• Pregnancy or lactation,
• AST/ALT >5 times the upper limit of normal or at baseline in patients with chronic liver disease
• Any condition that in the opinion of the investigator limits participation in the study.
• Patients who had received monoclonal antibodies against SARS-CoV-2