- age <18 years - pregnancy or breastfeeding - ongoing antiviral or antiretroviral treatment or hiv positive - ongoing anti-inflammatory treatment (corticosteroids) - ongoing or previous (1 month) chloroquine or hydroxychloroquine treatment - confirmed case of sars-cov-2 infection (positive pcr) at day 0 - positive serology for sars-cov-1 infection at day 0 - impossibility of signing the informed consent form - rejection of participation - working less than 3 days a week in the hospital clinic of barcelona. - any contraindication for hydroxychloroquine treatment: - hydroxychloroquine hypersensitivity or 4-aminoquinoline hypersensitivity - retinopathy, visual field or visual acuity disturbances - qt prolongation, bradycardia (<50bpm), ventricular tachycardia, other arrhythmias, as determined on day 0 ecg or medical history - potassium < 3 meq/l or ast or alt > 5 upper normal limit, as determined on day 0 blood test - previous myocardial infarction - myasthenia gravis - porphyria - glomerular clearance < 10ml/min - previous history of severe hypoglycaemia - ongoing treatment with antimalarials, antiarrhythmic, tricyclic antidepressants, selective serotonin reuptake inhibitors, natalizumab, quinolones, macrolides, agalsidase alfa and beta.

- age <18 years - pregnancy or breastfeeding - ongoing antiviral or antiretroviral treatment or hiv positive - ongoing anti-inflammatory treatment (corticosteroids) - ongoing or previous (1 month) chloroquine or hydroxychloroquine treatment - confirmed case of sars-cov-2 infection (positive pcr) at day 0 - positive serology for sars-cov-1 infection at day 0 - impossibility of signing the informed consent form - rejection of participation - working less than 3 days a week in the hospital clinic of barcelona. - any contraindication for hydroxychloroquine treatment: - hydroxychloroquine hypersensitivity or 4-aminoquinoline hypersensitivity - retinopathy, visual field or visual acuity disturbances - qt prolongation, bradycardia (<50bpm), ventricular tachycardia, other arrhythmias, as determined on day 0 ecg or medical history - potassium < 3 meq/l or ast or alt > 5 upper normal limit, as determined on day 0 blood test - previous myocardial infarction - myasthenia gravis - porphyria - glomerular clearance < 10ml/min - previous history of severe hypoglycaemia - ongoing treatment with antimalarials, antiarrhythmic, tricyclic antidepressants, selective serotonin reuptake inhibitors, natalizumab, quinolones, macrolides, agalsidase alfa and beta.