Cell Therapy With Treg Cells Obtained From Thymic Tissue (thyTreg) to Control the Immune Hyperactivation Associated With COVID-19 and/or Acute Respiratory Distress Syndrome (THYTECH2)

Inclusion Criteria: 1. Patient over 18 to 65 years of age 2. Patient Informed and non-opposed to the research by his medical doctor during hospitalization 3. Patient with clinical, radiological, gasometric and immunological criteria defined as: 1. Acute respiratory failure secondary to acute lung injury of noncardiogenic cause 2. Pulmonary abnormalities compatible with bilateral alveoloinsterstitial infiltrates by chest imaging (radiograph or scan) 3. PaO2/FiO2≤ 300 Presence of at least one of the following markers of inflammation: IL6 \> 40 pg/ml or ferritin \>300 ng/ml or CRP \>3 mg/dl or increasing over the last 24 hours Exclusion Criteria: 1. Pregnancy or breast feeding 2. Body mass index \>35 3. Patients not expected to survive 48 hours after enrolment based on clinical assessment 4. Patients with an extracorporeal respiratory support 5. Neutropenia (absolute neutrophil count \<1000/uL) 6. Thrombocytopenia (absolute neutrophil count \<50000/uL) 7. Positive serology for HBV, HCV, or HIV at Screening 8. Life expectancy of less than 6 months due to other pathologies 9. History of significant underlying pulmonary disease requiring oxygen therapy prior to inclusion. 10. Patients with a history of autoimmune diseases 11. Patients with a history of hematopoietic neoplasia or oncology disease 12. Patients with a history of hematopoietic or solid organ transplant 13. Patients with a congenital or induced immunodeficiency 14. Patients received thymoglobulin, basiliximab or any anti-T-cell therapies within 6 moths prior to the screening visit 15. Patients received other cell therapy in the last 12 months 16. Patients received intravenous immunoglobulin (IVIg) within 5 moths prior to the screening visit 17. Patients who have participated or is participating in a clinical research study evaluating COVID-19 or ARDS within 30 days prior to the screening visit