The ELISA test used by CeGaT has a CE mark and is approved by the FDA (Food and Drug Administration, USA) (EUA). The test is produced by EUROIMMUN; its reliability has been confirmed by several independent comparative scientific studies. It solely detects IgG antibodies against the S1 domain of the spike protein, including the immunologically relevant receptor-binding domain (RBD). The test thus achieves a specificity of 99.6% and ten days after onset of symptoms a sensitivity of 94.4%.
Since the WHO restricts International Units to quantitative neutralization tests, these semi-quantitative test results are reported in terms of ratios, which are a relative measure of the concentration of antibodies in the serum.
EUROIMMUN suggests the following interpretation of results:
Ratio < 0.8: negative Ratio ≥ 0.8 to < 1.1: borderline Ratio ≥ 1.1: positive.
The borderline range is a medical and methodological uncertainty range in which results cannot be interpreted as unambiguously positive or negative. It compensates for the limited precision of serological methods and avoids fluctuations in the qualitative evaluation from positive to negative and vice versa.
Target antigen: S1 Spike (RBD)
Antibody isotype: IgG
Cross-reactivity: No cross-reactions with other human pathogenic corona viruses (MERS-CoV, HCoV-229E, HCoV-NL63, HCoV-HKU1 or HCoV-OC43) have been observed (n=23).
Status: CE marked; approved by the FDA (EUA)