SARS-CoV-2 Omicron detection by antigen tests using saliva

Kaoru Murakami; Sumio Iwasaki; Satoshi Oguri; Kumiko Tanaka; Rigel Suzuki; Kasumi Hayasaka; Shinichi Fujisawa; Chiaki Watanabe; Satoshi Konno; Isao Yokota; Takasuke Fukuhara; Masaaki Murakami; Takanori Teshima

doi:10.1016/j.jcvp.2022.100109

SARS-CoV-2 Omicron detection by antigen tests using saliva

J Clin Virol Plus. 2022 Nov;2(4):100109. doi: 10.1016/j.jcvp.2022.100109. Epub 2022 Sep 13.

Authors

Kaoru Murakami^{1

2}, Sumio Iwasaki³, Satoshi Oguri³, Kumiko Tanaka¹, Rigel Suzuki⁴, Kasumi Hayasaka³, Shinichi Fujisawa³, Chiaki Watanabe³, Satoshi Konno⁵, Isao Yokota⁶, Takasuke Fukuhara⁴, Masaaki Murakami^{1

2

7}, Takanori Teshima^{3

8}

Affiliations

¹ Division of Molecular Psychoimmunology, Institute for Genetic Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
² Group of Quantum Immunology, Institute for Quantum Life Science, National Institute for Quantum and Radiological Science and Technology, Inage, Japan.
³ Division of Laboratory and Transfusion Medicine, Hokkaido University Hospital, Sapporo, Japan.
⁴ Department of Microbiology and Immunology, Hokkaido University Faculty of Medicine, Sapporo, Japan.
⁵ Department of Respiratory Medicine, Hokkaido University Faculty of Medicine, Sapporo, Japan.
⁶ Department of Biostatistics, Hokkaido University Faculty of Medicine, Sapporo, Japan.
⁷ Division of Molecular Neuroimmunology, National Institute for Physiological Sciences, National Institute of Natural Sciences, Okazaki, Japan Department of Biostatistics, Hokkaido University Faculty of Medicine, Sapporo, Japan.
⁸ Department of Hematology, Hokkaido University Faculty of Medicine, Sapporo, Japan.

Abstract

The Omicron emerged in November 2021 and became the predominant SARS-CoV-2 variant globally. It spreads more rapidly than ancestral lineages and its rapid detection is critical for the prevention of disease outbreaks. Antigen tests such as immunochromatographic assay (ICA) and chemiluminescent enzyme immunoassay (CLEIA) yield results more quickly than standard polymerase chain reaction (PCR). However, their utility for the detection of the Omicron variant remains unclear. We herein evaluated the performance of ICA and CLEIA in saliva from 51 patients with Omicron and 60 PCR negative individuals. The sensitivity and specificity of CLEIA were 98.0% (95%CI: 89.6-100.0%) and 100.0% (95%CI: 94.0-100.0%), respectively, with fine correlation with cycle threshold (Ct) values. The sensitivity and specificity of ICA were 58.8% (95%CI: 44.2-72.4%) and 100.0% (95%CI: 94.0-100.0%), respectively. The sensitivity of ICA was 100.0% (95%CI: 80.5-100.0%) when PCR Ct was less than 25. The Omicron can be efficiently detected in saliva by CLEIA. ICA also detects high viral load Omicron using saliva.

Keywords: ALP, alkaline phosphatase; CLEIA; CLEIA, chemiluminescent enzyme immunoassay; COVID-19; Ct, cycle threshold; ICA; ICA, immunochromatographic assay; Lumipulse; NPS, nasopharyngeal swab; PCR, polymerase chain reaction; RT-PCR, Real-time reverse transcription–quantitative PCR; SARS-CoV-2; Saliva; VOC, variant of concern.