Humoral Immune Response to SARS-CoV-2 Comparative Clinical Performance of Seven Commercial Serology Tests

Objectives: Severe acute respiratory syndrome coronavirus 2 ( SARS-CoV-2 ) serology tests are clinically useful to document prior SARS-CoV-2 infections. Data are urgently needed to select assays with optimal sensitivity at acceptable specificity for antibody detection. Methods: A comparative evaluation was performed of 7 commercial SARS-CoV-2 serology assays on 171 sera from 135 subjects with polymerase chain reaction-confirmed SARS-CoV-2 infection (71 hospitalized patients and 64 paucisymptomatic individuals). Kinetics of IgAlIgMl IgG seroconversion to viral N and S protein epitopes were studied, from 0 to 54 days after onset of symptoms. Cross-reactivity was verified on 57 prepandemic samples. Results: Wantai SARS-COV-2 Ab ELISA and Orient Gene COVID-19 IgGlIgM Rapid Test showed superior overall sensitivity for detection of SARS-CoV-2 antibodies. Elecsys Anti-SARS-CoV-2 assay and EUROIMMUN Anti-SARS-CoV-2 combined IgGlIgA showed acceptable sensitivity (>95%) vs the consensus result of all assays from 10 days post onset of symptoms. Wantai SARS-COV-2 Ab ELISA, Elecsys Anti-SARS-CoV-2 assay, and Innovita 2019-nCoV Ab rapid test showed least cross-reactivity, resulting in an optimal analytical specificity greater than 98%. Conclusions: Wantai SARS-COV-2 Ab ELISA and Elecsys Anti-SARS-CoV-2 assays are suitable for sensitive and specific detection of SARS-CoV-2 antibodies from 10 days after onset of symptoms.