* known hypersensitivity to hcq or other 4-aminoquinoline compounds * currently hospitalized * symptomatic with subjective fever, cough, or sore throat * current medications exclude concomitant use of hcq * concomitant use of other anti-malarial treatment or chemoprophylaxis * history of retinopathy of any etiology * psoriasis * porphyria * known bone marrow disorders with significant neutropenia (polymorphonuclear leukocytes \< 1500) or thrombocytopenia (\< 100 k) * concomitant use of digoxin, cyclosporin, cimetidine, or tamoxifen * known liver disease * known long qt syndrome * use of any investigational or non-registered drug or vaccine within 30 days preceding the first dose of the study drugs, or planned use during the study period

* known hypersensitivity to hcq or other 4-aminoquinoline compounds * currently hospitalized * symptomatic with subjective fever, cough, or sore throat * current medications exclude concomitant use of hcq * concomitant use of other anti-malarial treatment or chemoprophylaxis * history of retinopathy of any etiology * psoriasis * porphyria * known bone marrow disorders with significant neutropenia (polymorphonuclear leukocytes \< 1500) or thrombocytopenia (\< 100 k) * concomitant use of digoxin, cyclosporin, cimetidine, or tamoxifen * known liver disease * known long qt syndrome * use of any investigational or non-registered drug or vaccine within 30 days preceding the first dose of the study drugs, or planned use during the study period

- known hypersensitivity to hcq or other 4-aminoquinoline compounds - currently hospitalized - symptomatic with subjective fever, cough, or sore throat - current medications exclude concomitant use of hcq - concomitant use of other anti-malarial treatment or chemoprophylaxis - history of retinopathy of any etiology - psoriasis - porphyria - known bone marrow disorders with significant neutropenia (polymorphonuclear leukocytes < 1500) or thrombocytopenia (< 100 k) - concomitant use of digoxin, cyclosporin, cimetidine, or tamoxifen - known liver disease - known long qt syndrome - use of any investigational or non-registered drug or vaccine within 30 days preceding the first dose of the study drugs, or planned use during the study period

- known hypersensitivity to hcq or other 4-aminoquinoline compounds - currently hospitalized - symptomatic with subjective fever, cough, or sore throat - current medications exclude concomitant use of hcq - concomitant use of other anti-malarial treatment or chemoprophylaxis - history of retinopathy of any etiology - psoriasis - porphyria - known bone marrow disorders with significant neutropenia (polymorphonuclear leukocytes < 1500) or thrombocytopenia (< 100 k) - concomitant use of digoxin, cyclosporin, cimetidine, or tamoxifen - known liver disease - known long qt syndrome - use of any investigational or non-registered drug or vaccine within 30 days preceding the first dose of the study drugs, or planned use during the study period