The Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics) was developed to provide accurate, reliable detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated sensitivity, specificity, cross-reactivity, and agreement with a vesicular stomatitis virus-based pseudo-neutralisation assay for the Elecsys Anti-SARS-CoV-2 immunoassay. Sensitivity and agreement between the Elecsys Anti-SARS-CoV-2 immunoassay and pseudo-neutralisation assay measurements were evaluated using samples from patients with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection, a majority of whom were hospitalised. Specificity was evaluated using samples from routine diagnostic testing/blood donors collected pre-December 2019 and thus deemed negative for SARS-CoV-2-specific antibodies. Cross-reactivity was evaluated using samples containing a wide range of potentially cross-reacting analytes, purchased from commercial vendors. For sensitivity and specificity, point estimates and 95% confidence intervals (CIs) were calculated. Agreement between the Elecsys Anti-SARS-CoV-2 immunoassay and pseudo-neutralisation assay was calculated. Sensitivity of the Elecsys Anti-SARS-CoV-2 immunoassay in patients with prior PCR-confirmed SARS-CoV-2 infection was 99.5% (95% CI 97.0–100.0) at ≥14 days post-PCR confirmation. Overall specificity (n=10,453) was 99.80% (99.69–99.88). Only 4/792 samples containing potential cross-reacting analytes were reactive with the Elecsys Anti-SARS-CoV-2 immunoassay, resulting in an overall specificity in this cohort of 99.5% (98.6–99.9). Positive, negative and overall agreement (n=46) between Elecsys Anti-SARS-CoV-2 immunoassay and a pseudo-neutralisation assay were 86.4% (73.3–93.6), 100% (34.2–100) and 87.0% (74.3–93.9), respectively. The Elecsys Anti-SARS-CoV-2 immunoassay demonstrated high sensitivity (99.5% at ≥14 days post-PCR confirmation) and specificity (99.80%), supporting its use as a tool for identification of past SARS-CoV-2 infection, including in populations with low disease prevalence.

Antibodies against dsDNA of the IgM class were measured in sera of 352 patients with systemic lupus erythematosus, 81 blood donors and 189 patients with rheumatoid arthritis using a new ELISA based on human recombinant dsDNA as antigen. IgM anti-dsDNA antibodies were found in 52.3% of the sera from patients with systemic lupus erythematosus, but in none of the sera from 81 normal controls and 189 patients with rheumatoid arthritis. The association of these autoantibodies with 31 clinical and 37 laboratory parameters was calculated. There was a highly significant negative correlation between IgM anti-dsDNA antibodies and nephritis as well as all the laboratory parameters indicating renal disease (elevated serum creatinine concentration, proteinuria, erythrocyte casts in the urine). IgM anti-dsDNA antibodies indicate protection of lupus patients against the development of lupus nephritis. Further experiments will show whether application of IgM anti-dsDNA antibodies is effective in treating lupus nephritis.

Background: The Elecsys® Anti-SARS-CoV-2 immunoassay (Roche Diagnostics) was developed to provide an accurate and reliable method for the detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the sensitivity, specificity, and cross-reactivity of the Elecsys Anti-SARS-CoV-2 immunoassay. Methods: The performance of the Elecsys Anti-SARS-CoV-2 immunoassay was assessed at Roche Diagnostics (Penzberg, Germany). Sensitivity was evaluated using anonymised residual frozen samples from patients who had previously tested positive for SARS-CoV-2 infection by polymerase chain reaction (PCR); one or more consecutive samples were collected from patients at various timepoints after PCR confirmation. Specificity was evaluated using anonymised unselected residual frozen samples from routine diagnostic testing or from blood donors; all samples were collected before December 2019 and thus deemed negative for SARS-CoV-2-specific antibodies. Cross-reactivity was evaluated using anonymised frozen samples containing a wide range of potentially cross-reacting analytes, which were purchased from commercial vendors. For sensitivity and specificity, point estimates and 95% confidence intervals (CIs) were calculated. Results: Sensitivity of the Elecsys Anti-SARS-CoV-2 immunoassay in 496 samples from 102 patients with prior PCR-confirmed SARS-CoV-2 infection was 99.5% (95% CI 97.0-100.0) at ≥14 days after PCR confirmation. Overall specificity in 10,453 samples from routine diagnostic testing (n = 6305) and blood donors (n = 4148) was 99.80% (95% CI 99.69-99.88). Only 4/752 samples containing potential cross-reacting analytes were reactive with the Elecsys Anti-SARS-CoV-2 immunoassay, resulting in an overall specificity in this cohort of 99.5% (95% CI 98.6-99.9). Conclusion: The Elecsys Anti-SARS-CoV-2 immunoassay demonstrated a sensitivity of 99.5% at ≥14 days after PCR confirmation and a very high specificity of 99.80%. Our findings support the use of the Elecsys Anti-SARS-CoV-2 immunoassay as a tool for the identification of past SARS-CoV-2 infection, including in populations with a low disease prevalence.

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