Reluctance of patients and physicians in this transfusion study setting. Blood products have expired. New variants have appeared since the plasma collection period. Some recent publications question the effectiveness of transfusion.

COVID-19 (Corona Virus Disease 2019) hospitalized patients evolution is marked by the risk of worsening of the respiratory system during the second week of the disease. To date, treatments are currently being evaluated and none of them have shown to be effective in the care of these patients. The use of convalescent plasma is a passive immunotherapy. It has often been used in respiratory virus epidemic situations (during the 1918 or 2009 influenza pandemic, or during SARS-CoV-1 or MERS-CoV pandemic). Effects reported in literature are in favour of a beneficial impact of transfusion of these plasma without serious adverse effects reported.

PlasCoSSA is a randomized, controlled, triple-blinded, parallel clinical trial. This study tests the efficacy of convalescent plasma transfusion therapy in the early care of COVID-19 hospitalized patients outside intensive care units.

During SARS-CoV-2 infection, two clinical-biological phases can be observed: an initial viral phase followed by an immunological phase whose onset has been associated with more severe prognosis. Hospitalized patients with comorbidities or clinical risk factors have a higher risk of respiratory functions deterioration and significant risk to need intensive care.

Early transfusion of convalescent plasma (2 units of 200-230 mL of apheresis plasma inactivated by amotosalen) would prevent this secondary worsening and reduce the risk to be transferred to intensive care, length of stay and mortality. Considering clinical and biological manifestations of the disease, including coagulation disorders, endothelial alterations, immunological disorders, it seems interesting to compare this convalescent plasma with a SARS-CoV-2 lacking antibodies plasma.

Inclusion Criteria:

1. Age 18-90 years ;

2. COVID-19 confirmed case ;

3. Cases showing respiratory symptoms, checking at least one of the following criteria:

   1. Cough, dyspnea, respiratory rate > 24 breaths/min
   2. Oxygen saturation < 95% at rest in ambient air
   3. PaO2 < 70mmHg
   4. Scanographic pulmonary compatible with COVID in the absence of any other etiology

4. Risk of deterioration, checking at least one of the following comorbidity criteria :

   1. Chronic respiratory pathology
   2. Diabetes
   3. Cancer pathology
   4. Cardiovascular disease
   5. Chronic kidney failure
   6. Congenital or acquired immunodeficiency
   7. Cirrhosis at stage B
   8. Major sickle cell syndrome
   9. BMI > 30 kg/m2

OR one of the biological criteria :

1. D-dimer 1 µg/mL,
2. Lymphocytes < 0.8 G/L,
3. Ferritin > 300 µg/L,
4. Troponin I > 11 pg/mL or Troponin T > 24.8 pg/mL

Exclusion Criteria:

• Patients admitted in intensive care within the first 6 hours of hospital care,
• Patients after 10 days from the start of symptoms
• Age < 18 years and > 90 years
• Long-term oxygen-dependent patients (at home),
• Decompensated chronic cardiac, respiratory, urological pathology
• Patient refusing administration of blood products,
• Allergic reaction to plasma products,
• IgA deficiency,
• Contraindication to transfusion
• Ig transfusion within 30 days,
• Patient currently participating to another clinical trial,
• Pregnant women,
• No affiliated to the social security,
• Person deprived of liberty by a legal or administrative decision, person under guardianship