Among the rNP analytes available at the beginning of screening, we selected the rNP analyte from Genemedi (GM-rNP) as the starting analyte because the average R max for GM-rNP across 21 different α-NP antibodies was closest to its theoretical R max (data not provided). We subsequently obtained an rNP analyte from Acro Biosystems (AB-rNP) and determined, using the available α-NP antibodies at that time and a similar kinetic analysis as above, that it produced higher-affinity antibody interactions (on aggregate) than GM-rNP. Additional discussion of the differences between the two rNP analyte sources can found in the supplemental information. None of rNP analyte sources, however, allowed for testing the effects of the patient sample nasal matrix, so clinical SARS-CoV-2 patient nasopharyngeal swab samples stored in viral transport medium (VTM) were also sourced. Separate pools containing six high positives and six negatives (by qRT-PCR, Table ) were diluted to create the additional analyte source.