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.