The evaluation of a novel digital immunochromatographic assay with silver amplification to detect SARS-CoV-2

Yoko Kurihara; Yoshihiko Kiyasu; Yusaku Akashi; Yuto Takeuchi; Kenji Narahara; Sunao Mori; Tomonori Takeshige; Shigeyuki Notake; Atsuo Ueda; Koji Nakamura; Hiroichi Ishikawa; Hiromichi Suzuki

doi:10.1016/j.jiac.2021.07.006

The evaluation of a novel digital immunochromatographic assay with silver amplification to detect SARS-CoV-2

J Infect Chemother. 2021 Oct;27(10):1493-1497. doi: 10.1016/j.jiac.2021.07.006. Epub 2021 Jul 13.

Authors

Affiliations

¹ Division of Infectious Diseases, Department of Medicine, Tsukuba Medical Center Hospital, 1-3-1 Amakubo Tsukuba, Ibaraki, 305-8558, Japan; Department of Infectious Diseases, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan.
² Division of Infectious Diseases, Department of Medicine, Tsukuba Medical Center Hospital, 1-3-1 Amakubo Tsukuba, Ibaraki, 305-8558, Japan; Department of Infectious Diseases, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan. Electronic address: kiyasu-tuk@umin.ac.jp.
³ Department of Infectious Diseases, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan; Akashi Internal Medicine Clinic, 3-1-63 Asahigaoka, Kashiwara, Osaka, 582-0026, Japan.
⁴ Mizuho Medy Co., Ltd., 5-4 Fujinoki-machi, Tosu City, Saga, 841-0048, Japan.
⁵ Department of Clinical Laboratory, Tsukuba Medical Center Hospital, 1-3-1 Amakubo, Tsukuba, Ibaraki, 305-8558, Japan.
⁶ Department of Respiratory Medicine, Tsukuba Medical Center Hospital, 1-3-1 Amakubo, Tsukuba, Ibaraki, 305-8558, Japan.
⁷ Department of Infectious Diseases, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, 305-8576, Japan; Department of Infectious Diseases, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.

Abstract

Introduction: Rapid antigen tests are convenient for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, they have lower sensitivities than nucleic acid amplification tests. In this study, we evaluated the diagnostic performance of Quick Chaser_® Auto SARS-CoV-2, a novel digital immunochromatographic assay that is expected to have higher sensitivity than conventional antigen tests.

Methods: A prospective observational study was conducted between February 8 and March 24, 2021. We simultaneously obtained two nasopharyngeal samples, one for evaluation with the QuickChaser_® Auto SARS-CoV-2 antigen test and the other for assessment with reverse transcription PCR (RT-PCR), considered the gold-standard reference test. The limit of detection (LOD) of the new antigen test was compared with those of four other commercially available rapid antigen tests.

Results: A total of 1401 samples were analyzed. SARS-CoV-2 was detected by reference RT-PCR in 83 (5.9%) samples, of which 36 (43.4%) were collected from symptomatic patients. The sensitivity, specificity, positive predictive value, and negative predictive value were 74.7% (95% confidence interval (CI): 64.0-83.6%), 99.8% (95% CI: 99.5-100%), 96.9% (95% CI: 89.2-99.6%), and 98.4% (95% CI: 97.6-99.0%), respectively. When limited to samples with a cycle threshold (Ct) < 30 or those from symptomatic patients, the sensitivity increased to 98.3% and 88.9%, respectively. The QuickChaser_® Auto SARS-CoV-2 detected 34-120 copies/test, which indicated greater sensitivity than the other rapid antigen tests.

Conclusions: QuickChaser_® Auto SARS-CoV-2 showed sufficient sensitivity and specificity in clinical samples of symptomatic patients. The sensitivity was comparable to RT-PCR in samples with Ct < 30.

Keywords: COVID-19; Digital immuno-chromatographic antigen test; FUJI DRI-CHEM; QuickChaser Auto; SARS-CoV-2; Silver amplification.

Publication types

Observational Study

MeSH terms

Antigens, Viral
COVID-19*
Humans
Immunoassay
SARS-CoV-2*
Sensitivity and Specificity
Silver

Substances

Antigens, Viral
Silver