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. 2021 Aug 24;13(3):742-747.
doi: 10.3390/idr13030069.

Performance of Qualitative and Quantitative Antigen Tests for SARS-CoV-2 Using Saliva

Isao Yokota  1 , Takayo Sakurazawa  2 , Junichi Sugita  2 , Sumio Iwasaki  2 , Keiko Yasuda  2 , Naoki Yamashita  2 , Shinichi Fujisawa  2 , Mutsumi Nishida  2 , Satoshi Konno  3 , Takanori Teshima  2   4
Affiliations

Performance of Qualitative and Quantitative Antigen Tests for SARS-CoV-2 Using Saliva

Isao Yokota et al. Infect Dis Rep. .

Abstract

The rapid detection of SARS-CoV-2 is critical for the prevention of disease outbreaks. Antigen tests such as immunochromatographic assay (ICA) and chemiluminescent enzyme immunoassay (CLEIA) can yield results more quickly than PCR. We evaluated the performance of ICA and CLEIA using 34 frozen PCR-positive (17 saliva samples and 17 nasopharyngeal swabs [NPS]) and 309 PCR-negative samples. ICA detected SARS-CoV-2 in only 14 (41%) samples, with positivity rates of 24% in saliva and 59% in NPS. Notably, ICA detected SARS-CoV-2 in 5 of 6 samples collected within 4 days after symptom onset. CLEIA detected SARS-CoV-2 in 31 (91%) samples, with a positivity of 82% in saliva and 100% in NPS. These results suggest that the use of ICA should be limited to an earlier time after symptom onset and CLEIA is more sensitive and can be used in situations where quick results are required.

Keywords: CLEIA; COVID-19; Espline; ICA; Lumipulse; SARS-CoV-2; saliva.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Results of CLEIA and ICA. Relationships between (A) antigen concentrations of CLEIA and Ct values of PCR, and (B) ICA positivity/negativity and Ct values of PCR. Median and interquartile range of Ct values are shown in (B). Relationship between days from symptom onset and (C) antigen concentrations of CLEIA, (D) Ct values of PCR. Blue circles and yellow crosses represent saliva and NPS samples, respectively.
Figure 2
Figure 2
Histogram of antigen concentration. Upper and lower panels show frequency of PCR-positivity and PCR-negativity, respectively.
See this image and copyright information in PMC

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