The first eleven cases of SARS-CoV-2 Omicron variant infection in Japan: A focus on viral dynamics

Nobumasa Okumura; Shinya Tsuzuki; Sho Saito; Tomoya Saito; Satoshi Takasago; Masayuki Hojo; Noriko Iwamoto; Norio Ohmagari

doi:10.35772/ghm.2021.01124

This article has now been updated. Please use the final version.

The first eleven cases of SARS-CoV-2 Omicron variant infection in Japan: A focus on viral dynamics

Nobumasa Okumura, Shinya Tsuzuki, Sho Saito, Tomoya Saito, Satoshi Takasago, Masayuki Hojo, Noriko Iwamoto, Norio Ohmagari

Author information

Nobumasa Okumura
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
Shinya Tsuzuki
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
AMR Clinical Reference Center, National Center for Global Health and Medicine, Tokyo, Japan.
Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
Sho Saito
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
Tomoya Saito
Center for Emergency Preparedness and Response, National Institute of Infectious Diseases, Tokyo, Japan.
Satoshi Takasago
Department of Pediatrics, National Center for Global Health and Medicine, Tokyo, Japan.
Masayuki Hojo
Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan.
Noriko Iwamoto
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
Norio Ohmagari
Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan.
AMR Clinical Reference Center, National Center for Global Health and Medicine, Tokyo, Japan.

Keywords: COVID-19, B.1.1.529, threshold cycle, characteristics

JOURNAL FREE ACCESS Advance online publication

Article ID: 2021.01124

DOI https://doi.org/10.35772/ghm.2021.01124

The final version of this article is now available: Vol. 4 (2022), No. 2 pp. 133-136

Details

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant has spread rapidly worldwide. We report the clinical characteristics and threshold cycle (Ct) values of the first 11 patients infected with the SARS-CoV-2 Omicron variant in Japan. All patients were younger returnees from abroad; 10 patients had received two doses of vaccine. Estimated Ct values for the 11 patients were 6.0 (95% confidence interval [CI] 4.2-7.3) days for > 30, 10.6 (95% CI 9.5-11.9) days for > 35, 15.1 (95% CI 13.6-17.6) days for > 40, and 19.7 (95% CI 17.3-23.7)days for > 45. Our results provide important insights for indicators of infection control.

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