A comparison of antigen-based rapid test and RT-PCR test to diagnose COVID-19 and its infectivity

ABSTRACT Background. Medical screening and diagnostic cost and equipment availability has been a major obstacle to supposed-to-be extensive tracing, and overall, to the end of COVID-19 pandemic. Even though RT-PCR is the gold diagnostic standard, it is costly, lengthy, and may be unavailable in remote areas. Therefore, antigen-based COVID-19 rapid tests may be a solution to quickly detect and screen communities suspected of contracting COVID-19. Objective. This paper aims to observe how reliable antigen-based COVID-19 rapid tests are compared to RT-PCR testing. Material and methods. An observational cross-sectional study was performed on 101 samples to find the specificity, sensitivity, and accuracy of antigen-based rapid testing compared to RT-PCR testing performed on every individual. Then, a pattern between CT values and duration between onset of symptoms and testing to antigen-based rapid test result was observed to find a cut-off value such that the person may be deemed safe to exit isolation. Outcomes. A cut-off CT value of above 30.04 (p < 0.01) with a sensitivity of 66.7% and specificity of 77.8% (moderate accuracy) obtained from ROC analysis showed negative results on antigen-based rapid tests. The tests showed an overall accuracy of 67.3%, where results between the two tests were consistent. Conclusion. Therefore, an estimated CT value of 30 was moderately proved to be used as a criterion to end isolation and presume the person no longer sheds SARS-CoV-2. Keywords: antigen rapid test, COVID-19, RT-PCR, specificity, sensitivity