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. 2022 Feb;28(2):248-251.
doi: 10.1016/j.jiac.2021.10.026. Epub 2021 Nov 10.

Evaluation and clinical implications of the time to a positive results of antigen testing for SARS-CoV-2

Yusaku Akashi  1 , Yoshihiko Kiyasu  2 , Yuto Takeuchi  3 , Daisuke Kato  4 , Miwa Kuwahara  5 , Shino Muramatsu  6 , Atsuo Ueda  7 , Shigeyuki Notake  8 , Koji Nakamura  9 , Hiroichi Ishikawa  10 , Hiromichi Suzuki  11
Affiliations

Evaluation and clinical implications of the time to a positive results of antigen testing for SARS-CoV-2

Yusaku Akashi et al. J Infect Chemother. 2022 Feb.

Abstract

Introduction: Antigen tests for severe acute respiratory coronavirus 2 sometimes show positive lines earlier than their specified read time, although the implication of getting the results at earlier time is not well understood.

Methods: We prospectively collected additional nasopharyngeal samples from patients who had already tested positive for SARS-CoV-2 by reverse transcription PCR. The swab was used for an antigen test, QuickNavi™-COVID19 Ag, and the time periods to get positive results were measured.

Results: In 84 of 96 (87.5%) analyzed cases, the results of QuickNavi™-COVID19 Ag were positive. The time to obtain positive results was 15.0 seconds in median (inter quartile range: 12.0-33.3, range 11-736) and was extended in samples with higher cycle thresholds (p < 0.001). Positive lines appeared within a minute in 85.7% of cases and within 5 min in 96.4%.

Conclusion: QuickNavi™-COVID19 Ag immediately showed positive results in most cases, and the time to a positive reaction may have indicated the viral load.

Keywords: Antigen test; COVID-19; QuickNavi™-COVID19 Ag; SARS-CoV-2; Time to positive results.

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Conflict of interest statement

Denka Co., Ltd., and Mizuho Medy Co., Ltd. provided test kits free of charge. Regarding this study, Hiromichi Suzuki received lecture fees from Denka Co., Ltd., and Otsuka Pharmaceutical Co., Ltd., and a consultation fee from Mizuho Medy Co., Ltd. Daisuke Kato, Miwa Kuwahara, and Shino Muramatsu are employed by Denka Co., Ltd., the developer of QuickNavi™-COVID19 Ag.

Figures

Fig. 1
Fig. 1
Workflow of a drive-through testing site at Tsukuba Medical Center Hospital. Abbreviation: NP, nasopharynx.
Fig. 2
Fig. 2
Relationship between the time to get positive results and sample Ct values. Circles indicate cases with positive antigen tests. The results of linear regression analyses are shown as dotted lines, along with their p values.
Fig. 3
Fig. 3
Comparison of results between QuickNavi™-COVID19 Ag and DIA. Abbreviations; QuickNavi, QuickNavi™-COVID19 Ag; DIA, digital immunoassay.
See this image and copyright information in PMC

References

    1. World Health Organization Coronavirus disease (COVID-19) situation reports. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situatio...
    1. Centers for disease control and prevention. Testing strategies for SARS-CoV-2. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/sars-cov2-testin... - PubMed
    1. World Health Organization Antigen-detection in the diagnosis of SARS-CoV-2 infection using rapid immunoassays. https://www.who.int/publications/i/item/antigen-detection-in-the-diagnos...
    1. Obama H.C.J.T., Yousif N.A.M., Nemer L.A., Ngougoue P.M.N., Ngwa G.A., Teboh-Ewungkem M., et al. Preventing COVID-19 spread in closed facilities by regular testing of employees—an efficient intervention in long-term care facilities and prisons? PLoS One. 2021;16 doi: 10.1371/journal.pone.0249588. - DOI - PMC - PubMed
    1. Schwartz K.L., McGeer A.J., Bogoch Rapid antigen screening of asymptomatic people as a public health tool to combat COVID-19. CMAJ (Can Med Assoc J) 2021;193:E449–E452. doi: 10.1503/cmaj.210100. - DOI - PMC - PubMed