Comparative Evaluation of Nasopharyngeal and Oropharyngeal Swab Based Rapid SARS-CoV-2 Antigen Detection and Real-Time RT-PCR for Diagnosis of COVID-19 in Tertiary Care Hospital

Purpose To assess and compare the diagnostic accuracy of the GenBody COVID-19 Antigen kit (GenBody Inc., Cheonan, South Korea) available in the market with the gold standard reverse transcription-polymerase chain reaction (RT-PCR) assay to detect severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Methods Nasopharyngeal and oropharyngeal swabs were collected from suspected coronavirus disease 2019 (COVID-19) patients and tested by RT-PCR and GenBody Rapid antigen kit. Performance characteristic of the antigen kit was calculated. Results We tested nasopharyngeal swabs and oropharyngeal swabs (n=240). Amongst the 102 positive RT-PCR samples, the rapid antigen test detected 36 as positive, showing an overall sensitivity of 35.3%. All the samples detected positive with the antigen rapid test were also detected positive by RT-PCR. Conclusion The performance of the rapid antigen kit was good with respect to high viral load samples, whereas those with lower levels were missed. Unfortunately, the overall low sensitivity of the antigen kit does not allow using it alone as the frontline testing kit for COVID-19 diagnosis.