- severe infection, defined as need for invasive or non-invasive ventilator support, ecmo or shock requiring vasopressor support. - unable to take oral medication - known allergy to hcq or chloroquine - prolonged qt, defined as qtc ≥450 milliseconds for men and as qtc ≥470 for women - severely reduced lv function (ejection fraction<30%) - retinopathy - pregnancy or breast feeding - concomitant treatment with azithromycin, flecainide, amiodarone, digoxin, procainamide, propafenone, thioridazine, pimozide. - chronic chloroquine/ hcq treatment (within 1 month) - need for hemodialysis - participating in another rct for treatment of covid-19

- severe infection, defined as need for invasive or non-invasive ventilator support, ecmo or shock requiring vasopressor support. - unable to take oral medication - known allergy to hcq or chloroquine - prolonged qt, defined as qtc ≥450 milliseconds for men and as qtc ≥470 for women - severely reduced lv function (ejection fraction<30%) - retinopathy - pregnancy or breast feeding - concomitant treatment with azithromycin, flecainide, amiodarone, digoxin, procainamide, propafenone, thioridazine, pimozide. - chronic chloroquine/ hcq treatment (within 1 month) - need for hemodialysis - participating in another rct for treatment of covid-19