This is a multicenter, open-label, controlled, randomized phase 2 study designed to evaluate the safety and efficacy profile of GNS561 in patients with COVID-19.

Patients will be treated either with oral GNS561 plus standard of care or only standard of care. All patients in experimental arm will be treated for ten days. Study drug will be provided as oral capsules containing 200 mg of GNS561. Patients will be followed-up during hospitalization and after discharge.

Inclusion Criteria:

• Documented diagnosis of COVID-19 (diagnostic test performed in a certified laboratory).
• Clinical status: Hospitalized for moderate COVID-19 with News2 score between 5 and 6

Exclusion Criteria:

• Patient known to have intolerance or hypersensitivity to chloroquine or any quinoline derivates (quinine, tafenoquine, hydroxychloroquine, mefloquine).
• History of QT prolongation (QTc ≥ 500 ms) or QTc ≥ 500msec at screening or bradycardia < 50/mn
• Current use of loop diuretics and potassium supplementation or documented history of hypokalemia or hypokalemia < 3.5mmol/l at screening
• Prior allogeneic bone marrow transplantation or solid organ transplant in the past.
• Pregnant or breastfeeding patient, or expecting to conceive children within the projected duration of the trial, starting with the screening visit through 6 months after the last dose of study drugs.

age 18 or older at the time of enrolment for women and age 60 or older at the time of enrolment for men.