The evaluation results of proposed antigen rapid diagnostic tests for COVID-19: some possible factors might influence

Purpose In addition to existing gold standard qRT-PCR methods, there is a need to develop reliable rapid tests for infection control with early notification of COVID-19 cases to enable effective outbreak management. We evaluated the validity of the three Ag-RDT kits proposed by some companies in different countries by using qRT-PCR and analyzed its results. Methods Each of the three Ag-RDT kits (namely A, B, and C) was tested with 90 samples, consisting of samples with Ct <= 25, samples with Ct > 25, and negative SARS-CoV-2 PCR samples. Results This study showed that for samples with Ct > 25, all the three kits could not detect SARS-CoV-2 Ag (0% sensitivity) but showed 100% specificity. Meanwhile, for samples with Ct <= 25, kit C was the best (76.7% sensitivity and 100% specificity). The PPV of the three kits was 100%, but their NPV ranged 63-84.8%. Kit C showed the best accuracy (89.9%). Some factors might influence the results of evaluation, such as variation of virus proteins and transportation-storage of the kits. Conclusion The overall specificity of the three kits for all samples was high; however, all of them have not met the minimum performance requirements of >= 80% sensitivity for samples with Ct <= 25. The validation test is much necessary to be carried out by the authority in national health care to ensure the feasibility of the kit for point-of-care testing (POCT) of COVID-19. Some factors that might influence should be anticipated to increase their sensitivities and specificities.

Automated summary

This study evaluated the validity of three Ag-RDT kits from different companies, finding that they all had high specificity but failed to meet the minimum performance requirements for samples with Ct <= 25. Factors that may influence the results were also identified.