SARS-CoV-2 N-Antigen Quantification in Respiratory Tract, Plasma and Urine: Kinetics and Association with RT-qPCR Results oleh Delphine Parraud, Anne-Lise Maucotel, Maude Bouscambert, Florence Morfin, Laurent Bitker, Christian Chidiac, Nathalie De Castro, Emilie Frobert, Alexandre Gaymard, on behalf of the French COVID Cohort Study Group