Hydroxychloroquine Versus Placebo in COVID-19 Patients at Risk for Severe Disease

Inclusion Criteria: * Age ≥ 18 years old * Symptomatic infection with COVID-19 confirmed by positive RT-PCR SARS-CoV-2 or, failing that, by thorax CT-scan suggesting viral pneumopathy of peripheral predominance in a clinically significant context. * Diagnosis in the previous two calendar days or, for an asymptomatic patient at the time of virological diagnosis, onset of symptoms in the previous two calendar days. * Patient having at least one of the following risk factors for developing complications: * Age ≥75 years old * Age between 60 and 74 years old and presence of at least one comorbidity among the following: obesity (body mass index ≥ 30 kg/m²), arterial hypertension requiring treatment, diabetes mellitus requiring treatment * Need for supplemental oxygen to reach a peripheral capillary oxygen saturation of more than 94% (SpO2 \> 94%), or a ratio of partial oxygen pressure to the fraction of inspired oxygen less than or equal to 300 mmHg (PaO2/FiO2 ≤ 300 mmHg). * Patient affiliated to a social security scheme. * Written and signed consent of the patient or a relative or emergency inclusion procedure. Exclusion criteria * Last RT-PCR negative for SARS-CoV-2 * Peripheral capillary oxygen saturation less than or equal to 94% (SpO2 ≤ 94%) despite oxygen therapy greater than or equal to 3 L/min (\> 3 L/min) * Organ failure requiring admission to a critical or intensive care unit. * Comorbidity that is life threatening in the short-term (life expectancy \< 3 months) * Any reason that makes patient follow-up throughout the study impossible * Current treatment with hydroxychloroquine * Absolute contraindication to treatment with hydroxychloroquine (known hypersensitivity, retinopathy, concomitant treatment with risk of ventricular disorders, particularly torsades de pointe, known deficit of glucose-6-phosphate dehydrogenase, porphyria) * Hypokalaemia \< 3.5 mmol/L * Corrected QT prolongation (QTc ≥ 440 ms in men and 460 ms in women). * Child-Pugh's class C liver cirrhosis * Chronic kidney failure with estimated GFR ≤ 30 ml/min, or ≤ 40 ml/min in patients with concomitant treatment with azithromycin * Women who are pregnant, breastfeeding, or parturient