Background: Comparative data of SARS-CoV-2 IgM/IgG serology rapid diagnostic tests (RDTs) is scarce. We thus performed a head-to-head comparison of three RDTs.

Methods: In this unmatched case-control study, blood samples from 41 RT-PCR-confirmed COVID-19 cases and 50 negative controls were studied. The diagnostic accuracy of three commercially available COVID-19 RDTs: NTBIO (RDT-A), Orient-Gene (RDT-B), and MEDsan (RDT-C), against both a recombinant spike-expressing immunofluorescence assay (rIFA) and Euroimmun IgG ELISA, was assessed. RDT results concordant with the reference methods, and between whole blood and plasma, were established by the Kendall coefficient.

Results: COVID-19 cases’ median time from RT-PCR to serology was 22 days (interquartile range (IQR) 13–31 days). Whole-blood IgG detection with RDT-A, -B, and -C showed 0.93, 0.83, and 0.98 concordance with rIFA. Against rIFA, RDT-A sensitivity (SN) was 92% (95% CI: 78–98) and specificity (SP) 100% (95% CI: 91–100), RDT-B showed 87% SN (95% CI: 72–95) and 98% SP (95% CI: 88–100), and RDT-C 100% SN (95% CI: 88–100) and 98% SP (95% CI: 88–100). Against ELISA, SN and SP were above 90% for all three RDTs.

Conclusions: RDT-A and RDT-C displayed IgG detection SN and SP above 90% in whole blood. These RDTs could be considered in the absence of routine diagnostic serology facilities which were provided to the Geneva Reference Centre for Emerging Viral Diseases by the Swiss Red Cross and the Swiss National COVID-19  Science  Task  Force  (

MEDsan  GmbH,  Biological  Health  Solutions (Hamburg, Germany) hereafter, RDT-C.
When compared to rIFA,  RDT-C  (MEDsan)  appeared  to  be  the  most  satisfactory  of  the three  RDT  tested,  with  a concordance of 98%, a NPV of 100%, a PPV of 98%, a LR+ of 52, and an optimal LR-of 0.0.

Regarding the secondary endpoint (association with Euroimmun IgG ELISA) in whole blood, RDT-C (MEDsan) was also found to be close to optimal, with a concordance of 96%, a SN of 100%, a NPV of 100%, a SPof 96%, a PPV of 95%, and an optimal LR-of 0.0, butit also had the lowest LR+ (26.5) among the three RDTs.

To the best of our knowledge, only this study compared RDT performances against an immunoassay as the reference method.

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