Distribution of signal/cutoff ratios obtained for the EUROIMMUN ELISA for SARS-CoV-2 cases and other human coronavirus infections. Lines represent median values and interquartile ranges. * P value <.01. Abbreviations: ELISA, enzyme-linked immunosorbent assay; IgA, immunoglobulin A; IgG, immunoglobulin G; MERS, Middle East respiratory syndrome; S/CO, signal/cutoff; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.