Diagnostic performance of 7 rapid IgG/IgM antibody tests and the Euroimmun IgA/IgG ELISA in COVID-19 patients.

Abstract Objectives To evaluate the diagnostic performance of 7 rapid IgG/IgM tests and the Euroimmun IgA/IgG ELISA for antibodies against SARS-CoV-2 in COVID-19 patients. Methods Specificity was evaluated in 103 samples collected before January 2020. Sensitivity and time to seropositivity was evaluated in samples from 94 patients with COVID-19 confirmed with PCR on nasopharyngeal swab. Results Specificity [confidence interval] of lateral flow assays (LFA) was ≥ 91.3% [84.0-95.5] for IgM, ≥ 90.3% [82.9-94.8] for IgG, and ≥ 85.4% [77.2-91.1] for the combination IgM OR IgG. Specificity of the ELISA was 96.1% [90.1-98.8] for IgG and only 73.8% [64.5-81.4] for IgA. Sensitivity 14-25 days after onset of symptoms was ≥ 92.1% [78.5-98.0] to 100% [95.7-100] for IgG LFA compared to 89.5% [75.3-96.4] for IgG ELISA. Positivity of IgM OR IgG for LFA resulted in a decrease in specificity compared to IgG alone without a gain in diagnostic performance except for VivaDiag. The results for IgM varied significantly between the LFA with an average overall agreement of only 70% compared to 89% for IgG. The average dynamic trend to seropositivity for IgM was not shorter than for IgG. At time of admission to the hospital, the sensitivity of LFA was Conclusions Sensitivity for the detection IgG antibodies 14-25 days after onset of symptoms was ≥ 92.1% for all 7 LFA compared to 89.5% for the IgG ELISA. The results for IgM varied significantly and including IgM antibodies in addition to IgG for the interpretation of LFA did not improve the diagnostic performance.