8 or had an exclusion criteria, served as controls in Marseille centre. Patients in other centers did not receive hydroxychloroquine and served as controls. Symptomatic treatment and antibiotics as a measure to prevent bacterial super-infection was provided by investigators based on clinical judgment. Hydroxychloroquine was provided by the National Pharmacy of France on nominative demand. Clinical classification Patients were grouped into three categories: asymptomatic, upper respiratory tract infection (URTI) when presenting with rhinitis, pharyngitis, or isolated low-grade fever and myalgia, and lower respiratory tract infections (LRTI) when presenting with symptoms of pneumonia or bronchitis. PCR assay SARS-CoV-2 RNA was assessed by real-time reverse transcription-PCR [17]. Hydroxychloroquine dosage Native hydroxychloroquine has been dosed from patients’ serum samples by UHPLC-UV using a previously described protocol [18]. The peak of the chromatogram at 1.05 min of retention corresponds to hydroxychloroquine metabolite. The serum concentration of this metabolite is deduced from UV absorption, as for hydroxychloroquine concentration. Considering both concentrations provides an estimation of initial serum hydroxychloroquine concentration. Culture