A comparison of 7 commercial anti-SARS-CoV-2 antibody immunoassays

Serological testing in SARS-CoV-2 infection is gaining both patients' and clinicians' attention. Antibody assessment has potential multidirectional utility, hampered by the scarcity of clinical validation studies of the tests available on the market. Therefore, this study aimed to provide some evidence on the clinical utility of anti-SARS-CoV-2 commercial assays, based on the comparison of the results obtained with different methods.

The study included 52 samples from patients and healthy volunteers. The control samples (n = 20) were obtained during the SARS-CoV-2 pandemic. The case cohort consisted of 32 consecutive patients referred to the Diagnostyka medical laboratory for anti-SARS-CoV-2 antibody testing. For the purpose of this study, the MAGLUMI chemiluminescent immunoassay (CLIA) was chosen as a comparative method. All samples were tested with this method, as well as with the Euroimmun enzyme-linked immunosorbent assay (ELISA) and five different lateral flow immunoassays (LFIAs).

The results obtained in this study provide evidence for high overall concordance between the comparative CLIA method and both ELISA and different LFIAs. The agreement between CLIA and LFIAs was 92.3-98.0% for IgG and 90.0-96.1% for IgM, depending on the kit. The concordance between CLIA and ELISA was 92.3% for IgG and 75.0% for IgA (compared to the MAGLUMI CLIA IgM).

The results obtained in this study provide evidence for high overall concordance between the comparative CLIA method and different LFIAs. This could justify the use of LFIAs in some settings, where automated assays are not available, provided that some limitations are considered.