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• Anti-SARS-CoV-2 IgG specificity is critical for Covid-19 spread and prevalence studies. • A large collection of pre-pandemic samples is necessary for the assessment of assay specificity. • Specificity of Abbott Architect anti-SARS-CoV-2 IgG assay is high. • Sensitivity of both anti-SARS-CoV-2 IgG assays evaluated are high. We report our findings of test performance especially specificity of a fully automated Abbott Architect anti-SARS-CoV-2 CMIA IgG and Euroimmun anti-SARS-CoV-2 ELISA IgA/IgG in human plasma. We used positive cohort of 97 samples from Covid-19 patients or healthcare workers, collected at late time points from symptom onsets. We also included another cohort of 215 samples as negative controls, 78 of which had positive serology test results of other infectious diseases or autoimmunity. Assay specificity was assessed by using a total of 847 anonymized samples which were collected before the Covid-19 pandemic from local patient populations seeking clinical care for rheumatoid diseases, thyroid cancer, and therapeutic drug monitoring. Abbott IgG, Euroimmun IgG/IgA had high precision, demonstrated by both intra- and inter-day CVs of <2%. There was no Abbott or Euroimmun IgG assay cross reactivity in the 78 samples with positive serology of non-SARS-CoV-2 infectious diseases and positive autoimmune antibodies. The Abbott IgG has specificity of 99.6%, while Euroimmun IgG and IgA were as high as 91.5% and 71.5%, respectively. Our evaluation confirmed high specificity of the Abbott IgG assay, while it was lower for Euroimmun IgG. Euroimmun IgA has suboptimal specificity which may limit its clinical use. Assay sensitivity was high for both Abbott and Euroimmun IgG assays. [ABSTRACT FROM AUTHOR]

• Three nonautomated enzyme immunoassays for parvovirus B19 were compared. • IgG and IgM immunoassays from Biotrin, Euroimmun and Serion were compared. • Sensitivity, specificity, and concordance in 195 serum samples were calculated. • Agreement was obtained for 88.7% (IgG) and 75.9% (IgM) results. • Clinical interpretation by all three assays was identical in 83% of the samples. Diagnosis of parvovirus B19 (B19) infection in small-medium size clinical laboratories is most often done by nonautomated enzyme immunoassays (EIAs). Using 195 specimens we compared the analytical performance of Biotrin (Dublin, Ireland), Euroimmun (Lubeck, Germany), and Serion (Würzburg, Germany) EIAs. Sensitivity, specificity, and concordance to Biotrin assay were calculated. Overall complete agreement in the IgG and IgM results was 88.7% (173/195) and 75.9% (148/195) samples, respectively. When equivocal results were considered positive, Serion and Euroimmun highly agreed (>93.8%) with Biotrin in the IgG serology. Serion had better IgM sensitivity and specificity than Euroimmun when compared to Biotrin, although more Serion IgM equivocal results needed reflex testing. Clinical interpretation by all three assays was identical in 83% of the samples. We concluded that overall the performance of these assays was similar and both Serion and Euroimmun could be a suitable replacement for the Biotrin. [ABSTRACT FROM AUTHOR]