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Secondary transmission of SARS-CoV-2 during the first two waves in Japan: Demographic characteristics and overdispersion.
Ko, Yura K; Furuse, Yuki; Ninomiya, Kota; Otani, Kanako; Akaba, Hiroki; Miyahara, Reiko; Imamura, Tadatsugu; Imamura, Takeaki; Cook, Alex R; Saito, Mayuko; Suzuki, Motoi; Oshitani, Hitoshi.
  • Ko YK; Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan; Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Electronic address
  • Furuse Y; Institute for Frontier Life and Medical Sciences, Kyoto University, 53 kawaramachi, Shogoin, Sakyo-ku, Kyoto, Japan; Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, Japan. Electronic address: yukifuruse@gmail.com.
  • Ninomiya K; Graduate School of Pharmaceutical Sciences, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; National Institute of Public Health, 2-3-6 Minami, Wako-shi, Saitama 351-0197 Japan. Electronic address: kninomiya-mope@g.ecc.u-tokyo.ac.jp.
  • Otani K; Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan. Electronic address: otanik@niid.go.jp.
  • Akaba H; Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Electronic address: zh44893@gmail.com.
  • Miyahara R; Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan. Electronic address: rmiyahara@niid.go.jp.
  • Imamura T; Japan International Cooperation Agency, 5-25 Niban-cho, Chiyoda-ku, Tokyo 102-8012, Japan; Center for Postgraduate Education and Training, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo, Japan. Electronic address: imamura-t@ncchd.go.jp.
  • Imamura T; Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Electronic address: timamura@med.tohoku.ac.jp.
  • Cook AR; Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, 12 Science Drive 2, #10-01, Singapore. Electronic address: ephcar@nus.edu.sg.
  • Saito M; Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Electronic address: msaitop@med.tohoku.ac.jp.
  • Suzuki M; Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan. Electronic address: mosuzuki@niid.go.jp.
  • Oshitani H; Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Electronic address: oshitanih@med.tohoku.ac.jp.
Int J Infect Dis ; 116: 365-373, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1641323
ABSTRACT

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.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Observational study / Prognostic study Limits: Humans Country/Region as subject: Asia Language: English Journal: Int J Infect Dis Journal subject: Communicable Diseases Year: 2022 Document Type: Article

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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Observational study / Prognostic study Limits: Humans Country/Region as subject: Asia Language: English Journal: Int J Infect Dis Journal subject: Communicable Diseases Year: 2022 Document Type: Article