Change over Time in the Risk of Death among Japanese COVID-19 Cases Caused by the Omicron Variant Depending on Prevalence of Sublineages

Yuki Takahashi (), Hideo Tanaka, Yoshitaka Koga, Shunichi Takiguchi, Shigeru Ogimoto, Shizuyo Inaba, Hiroyuki Matsuoka, Yuka Miyajima, Takeshi Takagi, Fujiko Irie, Yoshihito Bamba, Fuyo Yoshimi, Tomoyuki Suzuki, Isao Araki, Chika Shirai, Sayuri Matsumoto, Motoyuki Shimizu, Toshiyuki Shibata, Hitomi Nagai, Masaru Kinoshita, Rie Fujita and Tsuyoshi Ogata
Additional contact information
Yuki Takahashi: Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan
Hideo Tanaka: Neyagawa City Public Health Center, Neyagawa 572-0838, Japan
Yoshitaka Koga: Tosu Public Health and Welfare Office of Saga Prefectural Government, Tosu 841-0051, Japan
Shunichi Takiguchi: Central Public Health Center of Miyazaki Prefectural Government, Kirishima 880-0032, Japan
Shigeru Ogimoto: Miyoshi Public Health Center of Tokushima Prefectural Government, Mima 778-0002, Japan
Shizuyo Inaba: Gifu Public Health Center of Gifu Prefectural Government, Gifu 504-0838, Japan
Hiroyuki Matsuoka: Iida Public Health Center of Nagano Prefectural Government, Iida 395-0034, Japan
Yuka Miyajima: Matsumoto Public Health Center of Nagano Prefectural Government, Matsumoto 390-0852, Japan
Takeshi Takagi: Isesaki Public Health Center of Gunma Prefectural Government, Isesaki 372-0024, Japan
Fujiko Irie: Tsuchiura Public Health Center of Ibaraki Prefectural Government, Tsuchiura 300-0812, Japan
Yoshihito Bamba: Ibaraki Prefectual Department of Public Health and Welfare, Mito 310-8555, Japan
Fuyo Yoshimi: Central Public Health Center of Ibaraki Prefectural Government, Mito 310-0852, Japan
Tomoyuki Suzuki: Shiga Prefectural Department of Public Health Care and Welfare, Otsu 520-8577, Japan
Isao Araki: Shiga Prefectural Health, Medical and Welfare Department, Otsu 520-8577, Japan
Chika Shirai: Hirakata City Public Health Center, Hirakata 573-0027, Japan
Sayuri Matsumoto: Higashiosaka City Public Health Center, Higashiosaka 578-0941, Japan
Motoyuki Shimizu: Higashiosaka City Public Health Center, Higashiosaka 578-0941, Japan
Toshiyuki Shibata: Suita City Public Health Center, Suita 564-0072, Japan
Hitomi Nagai: Ibaraki Public Health Center of Osaka Prefectural Government, Ibaraki 567-8585, Japan
Masaru Kinoshita: Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan
Rie Fujita: Kenou Public Health Center of Nagasaki Prefectural Government, Isahaya 854-0081, Japan
Tsuyoshi Ogata: Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan

IJERPH, 2023, vol. 20, issue 4, 1-9

Abstract: To assess temporal changes to the risk of death in COVID-19 cases caused by the Omicron variant, we calculated age-standardized case fatality rates (CFR) in patients aged ≥40 years over nine diagnostic periods (3 January to 28 August 2022) in ten Japanese prefectures (14.8 million residents). Among 552,581 study subjects, we found that there were 1836 fatalities during the isolation period (up to 28 days from date of onset). The highest age-standardized CFR (0.85%, 95% confidence interval (CI):0.78–0.92) was observed in cases diagnosed in the second 4-week period (January 31 to February 27), after which it declined significantly up to the 6th 4-week period (0.23%, 95% CI: 0.13–0.33, May 23 to June 19). The CFR then increased again but remained at 0.39% in the eighth period (July 18 to August 28). The CFR in cases with the BA.2 or BA.5 sublineages in the age range 60–80 years was significantly lower than that with BA.1 infections (60 years: 0.19%, 0.02%, 0.053%, respectively; 70 years: 0.91%, 0.33%, 0.39%; ≥80 years: 3.78%, 1.96%, 1.81%, respectively). We conclude that the risk of death in Japanese COVID-19 patients infected with Omicron variants declined through February to mid-June 2022.

Keywords: SARS-CoV-2; Omicron variant; case fatality rate; Japanese (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1660-4601/20/4/2779/pdf (application/pdf)
https://www.mdpi.com/1660-4601/20/4/2779/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jijerp:v:20:y:2023:i:4:p:2779-:d:1057921

Access Statistics for this article

IJERPH is currently edited by Ms. Jenna Liu

More articles in IJERPH from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().