Abstract
Introduction: Highly sensitive reagents for detecting SARS-CoV-2 antigens have been developed for accurate and rapid diagnosis till date. In this study, we aim to clarify the frequency of false-positive reactions and reveal their details in SARS-CoV-2 quantitative antigen test using an automated laboratory device.
Methods: Nasopharyngeal swab samples (n = 4992) and saliva samples (n = 5430) were collected. We measured their SARS-CoV-2 antigen using Lumipulse® Presto SARS-CoV-2 Ag and performed a nucleic acid amplification test (NAAT) using the Ampdirect™ 2019 Novel Coronavirus Detection Kit as needed. The results obtained from each detection test were compared accordingly.
Results: There were 304 nasopharyngeal samples and 114 saliva samples were positive in the Lumipulse® Presto SARS-CoV-2 Ag test. All positive nasopharyngeal samples in the antigen test were also positive for NAAT. In contrast, only three (2.6%) of all the positive saliva samples in the antigen test were negative for NAAT. One showed no linearity with a dilute solution in the dilution test. Additionally, the quantitative antigen levels of all the three samples did not decrease after reaction with the anti-SARS-CoV-2 antibody.
Conclusions: The judgment difference between the quantitative antigen test and NAAT seemed to be caused by non-specific reactions in the antigen test. Although the high positive and negative predictive value of this quantitative antigen test could be confirmed, we should consider the possibility of false-positives caused by non-specific reactions and understand the characteristics of antigen testing. We recommend that repeating centrifugation before measurement, especially in saliva samples, should be performed appropriately.
Keywords: Antigen; Detection; Non-specific reaction; SARS-CoV-2.
【저자키워드】 SARS-CoV-2, detection, Antigen, Non-specific reaction, 【초록키워드】 SARS-CoV-2, Saliva, Diagnosis, Novel coronavirus, Predictive value, Laboratory, Antigen, Nasopharyngeal swab, nucleic acid, Characteristics, anti-SARS-CoV-2 antibody, nasopharyngeal, NAAT, automated, nucleic acid amplification test, SARS-CoV-2 antigen, novel, nucleic acid amplification, Quantitative, non-specific, False-positive, SARS-CoV-2 antigens, Nasopharyngeal swab samples, Frequency, Negative predictive value, Dilution, reaction, Nasopharyngeal samples, false-positives, saliva samples, positive, reagent, nasopharyngeal swab sample, centrifugation, nasopharyngeal sample, decrease, performed, collected, caused, 【제목키워드】 False positive, Quantitative, the SARS-CoV-2,