Introduction: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the novel viral pathogen that causes coronavirus disease 2019 (COVID-19) in humans, has spread worldwide since its identification in late 2019. The pandemic produced an accelerated development of new serological techniques for diagnosis.
Methods: We evaluated two commercial assays for serological diagnosis of SARS-CoV-2 infection, approved by the Administración Nacional de Medicamentos, Alimentos y Tecnología Médica (ANMAT) in Argentina: Elecsys Anti-SARS-CoV-2; Roche for nucleocapsid total antibody detection, and VIDAS Anti-SARS-CoV-2 bioMérieux for spike protein IgG antibody detection. Sensitivity was assessed using a panel of 92 plasma samples from recovered COVID-19 patients who were positive for RT-PCR and positive for neutralizing antibodies by plaque reduction neutralization test (PRNT) and/or positive for IgG antibodies by indirect immunofluorescence assay (IFA). Specificity was determined studying 71 plasma samples collected during year 2018 prior to the COVID-19 pandemic. Assays were evaluated as stand-alone tests.
Results: Sensitivity was 97.8% and 98.9% for the Roche and bioMérieux assays, respectively, specificity: 98.5% (Roche) and 97.1% (bioMérieux), positive predictive value (PPV): 98.9% (Roche) and 97.8% (bioMérieux), and negative predictive value: (NPV) 97.2% (Roche) and 98.5% (bioMérieux). Additionally, Cohen's kappa coefficient demonstrated high concordance (k=0.950) between Roche and bioMérieux.
Discussion: In conclusion, our results evidenced a very good performance for the nucleocapsid antibody assay (Roche) and the spike protein antibody assay (bioMérieux), thus both platforms are equally adequate for indirect diagnosis of SARS-CoV-2 infection through total antibodies and IgG antibody detection, respectively.
Keywords: COVID-19; SARS-CoV-2 infection; antibody detection; diagnosis.
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