Comparative evaluation of six immunoassays for the detection of antibodies against SARS-CoV-2

ABSTRACT

ObjectivesSerologic techniques can serve as a complement to diagnose SARS-CoV-2 infection. The objective of our study was to compare the diagnostic performance of six immunoassays to detect antibodies against SARS-CoV-2 three lateral flow immunoassays (LFAs), one ELISA and two chemiluminescence assays (CLIAs). MethodsWe evaluated three LFAs (Alltest, One Step and SeroFlash), one ELISA (Dia.Pro) and 34 two CLIAs (Elecsys and COV2T). To assess the specificity, 60 pre-pandemic sera were 35 used. To evaluate the sensitivity, we used 80 serum samples from patients with 36 positive PCR for SARS-CoV-2. Agreement between techniques was evaluated using the kappa score (k). ResultsAll immunoassays showed a specificity of 100% except for SeroFlash (96.7%). Overall sensitivity was 61.3%, 73.8%, 67.5%, 85.9%, 88.0% and 92.0% for Alltest, One Step, SeroFlash, Dia.Pro, Elecsys and COV2T, respectively. Sensitivity increased throughout the first two weeks from the onset of symptoms, reaching sensitivities over 85% from 14 days for all LFAs, being One Step the most sensitive (97.6%), followed by SeroFlash (95.1%). Dia.Pro, Elecsys and COV2T showed sensitivities over 97% from 14 days, being 100% for COV2T. One Step showed the best agreement results among LFAs, showing excellent agreement with Dia.Pro (agreement=94.2%, k=0.884), COV2T (99.1%, k=0.981) and Elecsys (97.3%, k=0.943). Dia.Pro, COV2T and Elecsys also showed excellent agreement between them. ConclusionOne Step, Dia.Pro, Elecsys and COV2T obtained the best diagnostic performanc e results. All these techniques showed a specificity of 100% and sensitivities over 97% from 14 days after the onset of symptoms, as well as excellent levels of agreement.