Comparison of the Rapid Antigen Test to RT-qPCR in Diagnosis of SARS-CoV-2: A University Experience in Northern Cyprus

Abstract

Objective: As an alternative to RT-qPCR assays used in the diagnosis SARS-CoV-2, antigen-detecting rapid diagnostic tests (Ag-RDTs) are available for the qualitative detection of SARS-CoV-2 in nasopharyngeal swab samples. The aim of this study was to assess the accuracy and reliability of Ag-RDTs as a diagnostic method of detecting SARS-CoV-2 positive cases within a given population.
 Methods: In first phase of this investigation, 357 nasopharyngeal swab samples were screened for SARS-CoV-2 using Ag-RDTs. For the purposes of this study RT-qPCR was then applied to the same 357 nasopharyngeal swab samples in order to compare the reliability of the two detection methods. In the second phase of this investigation, Ag-RDTs were applied to an additional 75 nasopharyngeal swab samples that were already known to be RT-qPCR positive. 
 Results: In the first phase of this investigation, of the 357 samples screened using Ag-RDTs 14 samples were positive for SARS-CoV-2, in contrast, when RT-qPCR analysis was applied to the same 357 samples no SARS-CoV-2 samples were detected. Therefore, the false antigen positivity was determined to be at 3.9%. In the second phase of this investigation 75 RT-qPCR positive samples were re-evaluated with a rapid antigen test. Twenty-four of the 75 RT-qPCR positive sample were undetected.
 Conclusion: Solely relying on rapid antigen tests to detect SARS-CoV-2 infections in the community could consequently result in infectious individuals remaining in the population. The impact of false negative rapid test results can be reduced by implementing confirmatory RT-qPCR analysis particularly in symptomatic patients.