Figure 1.

A flow diagram of serologic screening. A total of 493 patients attending their planned clinic appointments received serologic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the study period. The flow diagram indicates the number of patients who tested positive, indeterminate, or negative using the Abbott SARS-CoV-2 IgG assay. Serum samples with an indeterminate test result on the Abbott assay were reprocessed using the S-protein/receptor binding domain (RBD) hybrid dual antigen binding assay (DABA) assay and the number of positive and negative results from this second assay are indicated. The 3 serologic groups that underwent subsequent comparative analysis are indicated (positive on Abbott assay [Abbott+], indeterminate on Abbott but positive on S-protein/RBD DABA assay [RBD+], and indeterminate on Abbott and negative on S-protein/RBD DABA assay [RBD−]).