Inclusion Criteria:  Adults aged > 18 years able to provide a valid informed consent to the study Documented COVID-19 by direct testing (positive PCR), with lung infiltrates at imaging (Chest-X ray or CT) and requirement of oxygen supplementation Less than 10 days form symptoms onset  Cytokine storm, using the criteria developed at Temple University (all of the three below criteria):  CRP > 46 mg/l Ferritin > 250 ng/ml  One variable of each of the three clusters below  Cluster 1  Albumin < 2.8 g/dl Lymphocytes <10.2 % of WBC Absolute neutrophil count > 11400/mm3  Cluster 2  ALT > 60 U/L AST > 87 U/L D-dimers > 4930 µg/l fibrinogen-equivalent-units (FEU). LDH >416 U/L High sensitivity troponin > 1.09 ng/ml  Cluster 3  Anion Gap at arterial blood gas < 6.8 mM Chloride > 106 mM Potassium > 4.9 mM BUN:creatinine ratio > 29 PaO2/FiO2 200-400 mmHg, while in oxygen therapy or continuous positive airway pressure (C-PAP) For women of childbearing potential and men: agreement to use contraception in the case of heterosexual intercourses before day 28 with a failure rate < 1% per year (bilateral tubal ligation, male sterilisation, hormonal contraceptives inhibiting ovulation, hormone-release or copper intrauterine devices). For men enrolled in the study, condom use is allowed.  Exclusion criteria:  Orotracheal intubation or ECMO support Active solid / hematologic cancer (including invasive non-melanoma skin cancer) Hypersensitivity or contra-indications to one of the investigational agents (including history of deep vein thrombosis / pulmonary thromboembolism within 12 weeks prior to screening) Other active concurrent viral, fungal or bacterial infections (including active tuberculosis/latent TB treated for less than 4 weeks, HIV and HCV/HBV infections) Pregnancy/breastfeeding Incapability to provide a valid informed consent (including age < 18 years old) Heart failure with NYHA >= 2 or any acute cardiac or vascular event requiring therapy in the previous 12 months Chronic renal failure (baseline GFR < 45 ml/min*1.73m2) Liver cirrhosis moderate / severe (Child-Pugh B or C) Chronic respiratory failure requiring O2 therapy or ventilation therapy at home Blood neutrophils <1000/mcL, platelet <50000/mcL, Hb levels <80 g/l ALT/AST > 5 times UNL  Use of any biologic agent or small molecule inhibitor and other investigational drugs in the previous 4 weeks or 5 half-lives (whichever is longer). Specific cut-offs for wash-out are required for the following therapies:  B-cell targeted therapies: 24 weeks or 5 half-lives (whichever is longer) TNF-inhibitors: 2 weeks or 5 half-lives (whichever is longer) JAK-inhibitors: 1 week or 5 half-lives (whichever is longer) Use of other immunosuppressive agents in the last 3 months (chronic use of topical steroids and systemic steroids with a dose ≤5 mg of prednisone equivalents is allowed) Use of any other investigational therapy for COVID-19 (including IV immunoglobulins, convalescent COVID-19 plasma or monoclonal antibodies) Impossibility to discontinue Strong inhibitors of OAT3 (such as probenecid) at study entry Any other condition judged by the local investigator as a contra-indication to eligibility Subjects who have received live vaccines within 4 weeks before the study or are planned to receive live vaccine in the first months after study enrolment.