Performance of an automated anti-SARS-CoV-2 immunoassay in prepandemic cohorts

Riester, E.; Krieter, B.; Findeisen, P.; Laimighofer, M.; Schoenfeld, K.; Laengin, T.; Niederhauser, C.

Background: The Elecsys(R) 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 specificity of the Elecsys Anti-SARS-CoV-2 immunoassay in prepandemic sample cohorts across five sites in Germany, Austria and Switzerland. Methods: Specificity of the immunoassay was evaluated using anonymised, frozen, residual serum and/or plasma samples from blood donors or routine diagnostic testing. All samples were collected before September 2019 and therefore presumed negative for SARS-CoV-2-specific antibodies. Cohorts included samples from blood donors, pregnant women and paediatric patients. Point estimates and 95% confidence intervals (CIs) were calculated. Results: Overall specificities for the Elecsys Anti-SARS-CoV-2 immunoassay in 9575 samples from blood donors (n = 6714) and diagnostic specimens (n = 2861) were 99.82% (95% CI 99.69-99.91) and 99.93% (95% CI 99.75-99.99), respectively. Among 2256 samples from pregnant women, specificity was 99.91% (95% CI 99.68-99.99). Among 205 paediatric samples, specificity was 100% (95% CI 98.22-100). Conclusion: The Elecsys Anti-SARS-CoV-2 immunoassay demonstrated a very high specificity across blood donor samples and diagnostic specimens from Germany, Austria and Switzerland. Our findings support the use of the Elecsys Anti-SARS-CoV-2 immunoassay as a potential tool for determination of an immune response following previous exposure to SARS-CoV-2 in the general population, including in blood donors, pregnant women and paediatric populations.