Fig. 2.

Detection of SARS-CoV-2 antigen in RT-qPCR tested nasopharyngeal swaps (negative PCR results are shown with a Ct value ≥ 45). Panel a compares the quantitative result of the antigen assay (AU/mL: arbitrary units) to the results of RT-qPCR carried out by two different laboratories (n = 196). Targets: N-gene for laboratory 1, E-gene for laboratory 2. b Laboratory 1 used the N-gene of SARS-CoV-2 as a screening assay and confirmed the result with the target Nsp2 (n = 110). The red line indicates the Ct value and the corresponding viral load of the reference sample of the Robert-Koch Institute for the screening target. c Laboratory 2 (n = 86): E-gene as screening target, RdRP as confirmatory target