Interpretive discrepancies caused by target values inter-batch variations in chemiluminescence immunoassay for SARS-CoV-2 IgM/IgG by MAGLUMIâ„¢.

Selingerova, Iveta; Valik, Dalibor; Gescheidtova, Lenka; Sramek, Vladimir; Cermakova, Zdenka; Zdrazilova-Dubska, Lenka

Plasma specimens from COVID-19 patients were double-tested for anti-SARS-CoV-2 antibodies by two different batches of MAGLUMIâ„¢ 2019-nCov IgM/IgG assays to evaluate IgM/IgG levels, qualitative interpretation, antibody kinetics and linearity of diluted specimen. Here we show that (i) high-level IgM specimens need to be diluted with negative human plasma but not kit diluents and (ii) measured anti-SARS-CoV-2 IgM/IgG concentrations are substantially higher with later marketed immunoassay batch leading to (iii) the change of qualitative interpretation (positive vs. negative) in 12.3 % of specimens measured for IgM, (iv) the informative time-course pattern of antibody production only when data from different immunoassay batches are not combined. This article is protected by copyright. All rights reserved.