Assessment of SARS CoV 2 serological tests for the diagnosis of COVID 19 through the evaluation of three immunoassays: Two automated immunoassays (Euroimmun and Abbott) and one rapid lateral flow immunoassay (NG Biotech)
Abstract Background The emergence of new SARS CoV 2 has promoted the development of new serological tests that could be complementary to RT PCR. Nevertheless, the assessment of clinical performances of available tests is urgently required as their use has just been initiated for diagnose. Objectives The aim of this study was to assess the performance of three immunoassays for the detection of SARS CoV 2 antibodies. Methods Two automated immunoassays (Abbott SARS CoV 2 CLIA IgG and Euroimmun Anti SARS CoV 2 ELISA IgG/IgA assays) and one lateral flow immunoassay (LFIA NG Test(r) IgG IgM COVID 19) were tested. 293 specimens were analyzed from patients with a positive RT PCR response, from patients with symptoms consistent with COVID 19 but exhibiting a negative response to the RT PCR detection test, and from control group specimens. Days since symptoms onset were collected from clinical information sheet associated with respiratory tract samples. Results Overall sensitivity for IgG was equivalent (around 80% for CLIA, ELISA and LFIA. Sensitivity for IgG detection, >14 days after onset of symptoms, was 100.0% for all assays. Overall specificity for IgG was greater for CLIA and LFIA (more than 98% compared to ELISA (95.8% Specificity was significantly different between IgA ELISA (78.9% and IgM LFIA (95.8% (p 0.05) The best agreement was observed between CLIA and LFIA assays (97% k 0.936) Conclusion Excellent sensitivity for IgG detection was obtained >14 days after onset of symptoms for all immunoassays. Specificity was also excellent for IgG CLIA and IgG LFIA. Our study shows that NG Test(r) is reliable and accurate for routine use in clinical laboratories.
Journal of Clinical Virology