Evaluation of the Diagnostic Accuracy of Nasal Cavity and Nasopharyngeal Swab Specimens for SARS-CoV-2 Detection via Rapid Antigen Test According to Specimen Collection Timing and Viral Load.

Sunjoo Kim,Jieun Jang,Hye-Ryun Yang,Seungjun Lee,Taejoon Kang,Kristin Widyasari

doi:10.3390/diagnostics12030710

Abstract

The rapid diagnosis of SARS-CoV-2 is an essential aspect in the detection and control of the spread of COVID-19. We evaluated the accuracy of the rapid antigen test (RAT) using samples from the nasal cavity and nasopharynx based on sample collection timing and viral load. We enrolled 175 patients, of which 71 patients and 104 patients had tested positive and negative, respectively, based on real time-PCR. Nasal cavity and nasopharyngeal swab samples were tested using STANDARD Q COVID-19 Ag tests (Q Ag, SD Biosensor, Korea). The sensitivity of the Q Ag test was 77.5% (95% confidence interval [CI], 67.8–87.2%) for the nasal cavity and 81.7% (95% [CI, 72.7–90.7%) for the nasopharyngeal specimens. The RAT results showed a substantial agreement between the nasal cavity and nasopharyngeal specimens (Cohen’s kappa index = 0.78). The sensitivity of the RAT for nasal cavity specimens exceeded 89% for <5 days after symptom onset (DSO) and 86% for Ct of E and RdRp < 25. The Q Ag test performed fairly well, especially in the early DSO when a high viral load was present, and the nasal cavity swab can be considered an alternative site for the rapid diagnosis of COVID-19.

Highlights

Publisher’s Note: MDPI stays neutralSince the initial outbreak in 2019, SARS-CoV-2 has caused the historic COVID-19 pandemic and remains an ongoing serious public health concern worldwide
We evaluated the analytical performance of rapid antigen test (RAT) for the detection of SARS-CoV-2 from nasopharyngeal and nasal swab specimens
Is the nasal cavity an optimal site for specimen answer these questions, we evaluated the performance of the Q Ag test kit, a RAT that has collection for RAT? Third, does the color intensity of RAT correlate with viral load? To been widely used in South Korea, using specimens that were taken from the nasopharynx and the nasal cavity

Summary

Introduction

Publisher’s Note: MDPI stays neutralSince the initial outbreak in 2019, SARS-CoV-2 has caused the historic COVID-19 pandemic and remains an ongoing serious public health concern worldwide. The starting point for managing the spread of COVID-19 is the rapid and accurate detection of SARS-CoV-2. The molecular diagnostic method features very high sensitivity and is regarded as the gold standard of detection, it has some drawbacks: carryover contamination, the necessity of well-trained technicians, expensive equipment, and difficulty of implementation in resource-poor countries [1,2]. It takes several hours or even a few days to obtain a result from a molecular test, which hampers immediate response to positive cases [3]. An antigen test is an immunoassay that detects the presence of a specific with regard to jurisdictional claims in published maps and institutional affiliations

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