TY - JOUR
T1 - Secondary transmission of SARS-CoV-2 during the first two waves in Japan
T2 - Demographic characteristics and overdispersion
AU - Ko, Yura K.
AU - Furuse, Yuki
AU - Ninomiya, Kota
AU - Otani, Kanako
AU - Akaba, Hiroki
AU - Miyahara, Reiko
AU - Imamura, Tadatsugu
AU - Imamura, Takeaki
AU - Cook, Alex R.
AU - Saito, Mayuko
AU - Suzuki, Motoi
AU - Oshitani, Hitoshi
N1 - Funding Information:
Y.K.K. and H.O. designed the research. Y.K.K, Y.F. K.N. K.O. H.K. R.M. and T.I. managed and curated the data. Y.K.K. performed the research. Y.K.K. Y.F. and H.O. analyzed the data. T.I. A.R.C. M.S. and M.S. interpreted the data. Y.K.K wrote the first draft of the manuscript, which was revised by all authors. All authors approved the final version of the manuscript. This study did not require ethical approval because the data were public, anonymous, and collected as part of the outbreak response. The work was supported in part by the Emerging/Re-emerging Infectious Diseases Project of Japan from the Japan Agency for Medical Research and Development, AMED under Grant Number JP19fk0108104. The work was also supported by the Health, Labour and Welfare Policy Research Grants, Research on Emerging and Re-emerging Infectious Diseases and Immunization (Grant number 20HA2007), and Japanese Society for the Promorion of Science (JSPS) KAKENHI Grant Number JP21K19624. Y.K.K. received a scholarship from Takeda Science Foundation. We thank all the members of local governments, public health centers and institutes, and the National Institute of Infectious Diseases, Japan, for their great efforts in surveillance, laboratory testing, epidemiologic investigations, and data collection. We also thank all members of the National Task Force for COVID-19; volunteers; and research assistants in the Cluster Response Team, including Kozue Amemiya, Kyoko Arai, Yuki Arakawa, Kayoko Chishima, Aya Fujiwara, Ami Fukunaga, Yoko Fushiki, Yoko Hamasaki, Keiya Inoue, Sachi Ishida, Naomi Ikeda, Mariko Kanamori, Toshiya Kawakami, Tsuyoki Kawashima, Shunta Kikuchi, Tomoe Mashiko, Rie Masuda, Yoko Matsuoka, Yoshikazu Miyasato, Emiko Mukai, Yugo Nagae, Hanae Nagata, Takeshi Nakagawa, Yosuke Nakazawa, Yoshifumi Nin, Yukiyo Nitta, Yoshua K. Nomura, Mariko Nozaki, Tetsuro Oda, Yamato Okura, Yu Sadachi, Akiko Sakai, Junko Sakurai, Kazuaki Sano, Misaki Sasanami, Asako Sato, Sayaka Suzuki, Ayaka Takeuchi, Hiroto Tanaka, Fumie Tokuda, Mutsumi Tokunaga, Akira Toyama, Shogo Yaegashi, Yoko Yamagiwa, Lisa Yamasaki, Masato Yamauchi, Masayo Yano, and Fumi Yoshimatsu.
Funding Information:
The work was supported in part by the Emerging/Re-emerging Infectious Diseases Project of Japan from the Japan Agency for Medical Research and Development, AMED under Grant Number JP19fk0108104 . The work was also supported by the Health, Labour and Welfare Policy Research Grants, Research on Emerging and Re-emerging Infectious Diseases and Immunization (Grant number 20HA2007), and Japanese Society for the Promorion of Science (JSPS) KAKENHI Grant Number JP21K19624. Y.K.K. received a scholarship from Takeda Science Foundation.
Publisher Copyright:
© 2022 The Authors
PY - 2022/3
Y1 - 2022/3
N2 - Objectives: Super-spreading events caused by overdispersed secondary transmission are crucial in the transmission of COVID-19. However, the exact level of overdispersion, demographics, and other factors associated with secondary transmission remain elusive. In this study, we aimed to elucidate the frequency and patterns of secondary transmission of SARS-CoV-2 in Japan. Methods: We analyzed 16,471 cases between January 2020 and August 2020. We generated the number of secondary cases distribution and estimated the dispersion parameter (k) by fitting the negative binomial distribution in each phase. The frequencies of the secondary transmission were compared by demographic and clinical characteristics, calculating the odds ratio using logistic regression models. Results: We observed that 76.7% of the primary cases did not generate secondary cases with an estimated dispersion parameter k of 0.23. The demographic patterns of primary-secondary cases differed between phases, with 20–69 years being the predominant age group. There were higher proportions of secondary transmissions among older individuals, symptomatic patients, and patients with 2 days or more between onset and confirmation. Conclusions: The study showed the estimation of the frequency of secondary transmission of SARS-CoV-2 and the characteristics of people who generated the secondary transmission.
AB - Objectives: Super-spreading events caused by overdispersed secondary transmission are crucial in the transmission of COVID-19. However, the exact level of overdispersion, demographics, and other factors associated with secondary transmission remain elusive. In this study, we aimed to elucidate the frequency and patterns of secondary transmission of SARS-CoV-2 in Japan. Methods: We analyzed 16,471 cases between January 2020 and August 2020. We generated the number of secondary cases distribution and estimated the dispersion parameter (k) by fitting the negative binomial distribution in each phase. The frequencies of the secondary transmission were compared by demographic and clinical characteristics, calculating the odds ratio using logistic regression models. Results: We observed that 76.7% of the primary cases did not generate secondary cases with an estimated dispersion parameter k of 0.23. The demographic patterns of primary-secondary cases differed between phases, with 20–69 years being the predominant age group. There were higher proportions of secondary transmissions among older individuals, symptomatic patients, and patients with 2 days or more between onset and confirmation. Conclusions: The study showed the estimation of the frequency of secondary transmission of SARS-CoV-2 and the characteristics of people who generated the secondary transmission.
KW - COVID-19
KW - Dispersion parameter
KW - Overdispersion
KW - Secondary transmission
KW - Super-spreading events
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U2 - 10.1016/j.ijid.2022.01.036
DO - 10.1016/j.ijid.2022.01.036
M3 - Article
C2 - 35066162
AN - SCOPUS:85124415981
SN - 1201-9712
VL - 116
SP - 365
EP - 373
JO - International Journal of Infectious Diseases
JF - International Journal of Infectious Diseases
ER -
