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Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.

Volume 32, Number 11—November 2026

Dispatch

Post–COVID-19 Expansion of Streptococcus pyogenes Lineages Causing Toxic Shock Syndrome, Japan, 2023–2024

Tadayoshi IkebeComments to Author , Hitoshi Otsuka, Mari Sasaki, Takahiro Yamaguchi, Yoshimi Date, Yu Kazawa, Kazuki Saito, Kaho Ikeda, Rumi Okuno, Yukihiro Akeda, and The Working Group for Beta-Hemolytic Streptococci in Japan1
Author affiliation: National Institute of Infectious Diseases, Tokyo, Japan (T. Ikebe, Y. Akeda); Yamaguchi Prefectural Institute of Public Health and Environment, Yamaguchi, Japan (H. Otsuka); Oita Prefectural Institute of Health and Environment, Oita, Japan (M. Sasaki); Osaka Institute of Public Health, Osaka, Japan (T. Yamaguchi); Kanagawa Prefectural Institute of Public Health, Kanagawa, Japan (Y. Date); Fukushima Prefectural Institute of Public Health, Fukushima, Japan (Y. Kazawa); Toyama Institute of Health, Toyama, Japan (K. Saito, K. Ikeda); Tokyo Metropolitan Institute of Public Health, Tokyo (R. Okuno)

Main Article

Figure 2

Isolates of M1 lineages by month in study of post–COVID-19 expansion of Streptococcus pyogenes lineages causing toxic shock syndrome, Japan, 2023–2024. y-axis indicates the number of calculated 100% isolates of each lineage: A) M1UK; B) M113SNPs; C) M1global. Vertical lines separate pre–COVID-19, COVID-19, and post–COVID-19 periods.

Figure 2. Isolates of M1 lineages by month in study of post–COVID-19 expansion of Streptococcus pyogenes lineages causing toxic shock syndrome, Japan, 2023–2024. y-axis indicates the number of calculated 100% isolates of each lineage: A) M1UK; B) M113SNPs; C) M1global. Vertical lines separate pre–COVID-19, COVID-19, and post–COVID-19 periods.

Main Article

1Additional members of this group who contributed data are listed at the end of this article.

Page created: September 08, 2026
Page updated: October 16, 2026
Page reviewed: October 16, 2026
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