Evaluation of the Omicron variant by RT-PCR and rapid antigen testing (ExacTest™ COVID-19 Antigen Rapid Test)

ABSTRACT

Purpose: The present study aims to compare the results of the COVID-19 rapid antigen test (ExacTest™ COVID-19 Antigen Rapid Test) and real-time polymerase chain reaction (RT-PCR) test in samples of people suspected of coronavirus disease (COVID-19). Materials and methods: Among the samples submitted between January 2022 and March 2022 with suspicion of COVID-19, 299 samples subject to simultaneous COVID-19 RADT (Rapid Antigen Detection Test) and RT- PCR were evaluated retrospectively. The Real-Time PCR test was studied with the DS CORONEX COVID-19 Multiplex Real time-qPCR Test Kit (DS Nano and Biotechnology Product Tracing and Tracking Co., Turkey) and the rapid antigen test was studied by the immunochromatographic method with ExacTest™ COVID-19 Antigen Rapid Test Cassette kit (General Diagnostica inc., California, USA). Ag-RDT test results were evaluated with the fluorescent immunoassay analyzer (FIATEST Analyzer, Hangzhou Alltest Biotech Co., Ltd. China). Results: RT-PCR test was positive in 53 (17.7%) samples. The RADT's sensitivity was found 88.7 (95% Cl 77.0-95.7), specificity 98.0 (95% Cl 95.3-99.3), positive predictive value 90.4 (95% Cl 79.7-95.8), negative predictive value 97.6 (95% Cl 95.0-98.8), and accuracy 96.3 (95% Cl 93.5-98.2). Sample sensitivities of patients under and over 18 years of age have been identified as 75 (95% Cl 19.4-99.4) and 89.8 (95% Cl 77.8-96.6), respectively. The sensitivity of patients with and without symptoms was 95.5 (95% Cl 77.2-99.9) and 83.9 (95% Cl 66.3-94.6), respectively. For samples with a cycle threshold (Ct) of <20, 20-<25, 25-<30 and 30-<35, the concordance of testing was 100%, 92.9%, 78.9% and 80%, respectively. Conclusion: The rapid antigen kit studied complies with the use criteria recommended by the World Health Organization and is quite useful for the rapid diagnosis of symptomatic patients in COVID-19. © 2022, Pamukkale University. All rights reserved.