Validation of the COVID-19 IgG/IgM Rapid Test Cassette (BNCP ­ 402 and BNCP402) in a South African setting

ABSTRACT

Background: Different diagnostic tools could improve early detection of coronavirus disease 2019 (COVID-19). A number of antibody-based serological point-of-care tests have been developed to supplement real-time reverse transcriptase polymerase chain reaction (RT-PCR)-based diagnosis. This study describes the validity of an antibody test, namely the immunoglobulin G (IgG)/immunoglobulin M (IgM) Rapid Test Cassette® (BNCP ­ 402 and BNCP402), manufactured by Spring Healthcare Services. Methods: A prospective cohort validation study was undertaken at Chris Hani Baragwanath Academic Hospital between 16 July 2020 and 12 August 2020. A total of 101 patients admitte as COVID-19 cases under investigation were included in the study. They were divided into two categories depending on time since symptom onset testing performed within seven days (early cohort) and after seven days (late cohort). The rapid antibody test was compared to the RT-PCR. Results: Overall, the test has a sensitivity and specificity of 85.2% and 80.0%, respectively, for a combination of IgG and IgM. Sensitivity and specificity of IgG testing alone were 81.5% and 85%. Sensitivity improved for testing with increasing time from symptom onset; however, specifity was not significantly different. Conclusion: The study data adds to the body of evidence that because of relatively low sensitivity and specificity, there is a limited role for antibody-based point-of-care testing in the acute phase of COVID-19 infection, as was the case with this IgG/IgM Rapid Test Cassette (BNCP ­ 402 and BNCP402). There may exist a role for such testing in patients recovered from prior COVID-19 infection or in seroprevalence studies; however, additional evaluations at later timepoints from symptom onset are required.