Patient Inclusion Criteria

- Age >18 years- Hospital admission with proven SARS2-Covid19 infection- Hypoxemic respiratory failure (SaO2 <94%, PaO2 <9kPa)- Ability to give informed consent.

Patient Exclusion Criteria

- Pre-existing chronic pulmonary disease- Former diagnosis of Interstitial pulmonary disease- Former diagnosis of COPD 4 or FEV1<30%pred- Previous DLCO <45%- Total lung capacity (TLC) < 60% of predicted- Lung cancer with non-surgical treatment in last year- Chronic home oxygen treatment- Pre-existing heart failure with a known left ventricular ejection fraction <40%- Active treatment of hematological or non-hematological cancer with targeted, immuno- or chemotherapy or targeted radiotherpay in the last year- Inability to provide informed consent- Any subject who had received any investigational medication within 1 month prior to the start of this study or who is scheduled to receive another investigational drug during the course of this study- Active liver disease, porphyria or elevations of serums transaminases >5 x ULN (upper limit of normal) or bilirubin > 1.5 x ULN- History or suspicion of inability to cooperate adequately.- White blood count < 4.0^109/l- Hemoglobin < 6.0 mmol/l- Thrombocytes < 100^109/l- Pregnant female subjects- Breastfeeding female subjects- Use of strong Cyp3A4 inductors, including the following drugs: Carbamazepine, efavirenz, enzalutamide, fenobarbital, fenytoine, hypericum, mitotaan, nevirapine, primidon, rifabutine, rifampicine- Concomittant use of chloroquine or hydroxychloroquine.- QTc >500msec at baseline.