A Clinical Usefulness of Quantitative Antigen Test for COVID-19 Diagnosis

Background: The reverse-transcription polymerase chain reaction (RT-PCR) test is currently the gold standard for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, until date, few studies have reported on the performance of the quantitative antigen test. In this study, we attempted to validate the performance of a quantitative antigen test at a medium-sized hospital. Materials and Methods: A total of 149 nasopharyngeal swabs from 115 hospitalized patients were tested in parallel by-SARS-CoV-2 RT-PCR and the quantitative antigen test, and the results were compared. We assessed: (1) the detection rates with the quantitative antigen test and RT-PCR;(2) the factors associated with discordant results;(3) correlation of antigen concentration over the course of the clinical illness.