Diagnostic accuracy of Augurix COVID‐19 IgG serology rapid test

Andrey, Diego O.; Cohen, Patrick; Meyer, Benjamin; Torriani, Giulia; Yerly, Sabine; Mazza, Lena; Calame, Adrien; Arm‐Vernez, Isabelle; Guessous, Idris; Stringhini, Silvia; Roux‐Lombard, Pascale; Fontao, Lionel; Agoritsas, Thomas; Stirnemann, Jerôme; Reny, Jean‐Luc; Siegrist, Claire‐Anne; Eckerle, Isabella; Kaiser, Laurent; Vuilleumier, Nicolas

AIMS: To validate the diagnostic accuracy of the Augurix SARS‐CoV‐2 IgM/IgG rapid immunoassay diagnostic test (RDT) for COVID‐19. METHODS: In this unmatched 1:1 case‐control study, blood samples from 46 real‐time RT‐PCR‐confirmed SARS‐CoV‐2 hospitalized cases and 45 healthy donors (negative controls) were studied. Diagnostic accuracy of the IgG RDT was assessed against both an in‐house recombinant spike‐expressing immunofluorescence assay (rIFA), as an established reference method (primary endpoint), and the Euroimmun SARS‐CoV2 IgG enzyme‐linked immunosorbent assays (ELISA) (secondary endpoint). RESULTS: COVID‐19 patients were more likely to be male (61% versus 20%; p=0.0001) and older (median 66 versus 47 years‐old; p<0.001) than controls. Whole blood IgG‐RDT results showed 86% and 93% overall Kendall concordance with rIFA and IgG ELISA, respectively. IgG RDT performances were similar between plasma and whole blood. Overall, RDT sensitivity was 88% (95% confidence interval [95%CI]: 70‐96), specificity 98% (95%CI: 90‐100), PPV 97% (95%CI: 80‐100) and NPV 94% (95%CI: 84‐98). The IgG‐RDT carried out from 0 to 6 days, 7 to 14 days and >14 days after the SARS‐CoV‐2 RT‐PCR test displayed 30%, 73% and 100% positivity rates in the COVID‐19 group, respectively. When considering samples taken >14 days after RT‐PCR diagnosis, NPV was 100% (95%CI:90‐100), and PPV was 100% (95%CI:72‐100). CONCLUSIONS: The Augurix IgG‐RDT done in whole blood displays a high diagnostic accuracy for SARS‐CoV‐2 IgG in high COVID‐19 prevalence settings, where its use could be considered in the absence of routine diagnostic serology facilities.