Secondary transmission of SARS-CoV-2 during the first two waves in Japan: Demographic characteristics and overdispersion

Yura K Ko; Yuki Furuse; Kota Ninomiya; Kanako Otani; Hiroki Akaba; Reiko Miyahara; Tadatsugu Imamura; Takeaki Imamura; Alex R Cook; Mayuko Saito; Motoi Suzuki; Hitoshi Oshitani

International Journal of Infectious Diseases (Mar 2022)

Secondary transmission of SARS-CoV-2 during the first two waves in Japan: Demographic characteristics and overdispersion

Yura K Ko,
Yuki Furuse,
Kota Ninomiya,
Kanako Otani,
Hiroki Akaba,
Reiko Miyahara,
Tadatsugu Imamura,
Takeaki Imamura,
Alex R Cook,
Mayuko Saito,
Motoi Suzuki,
Hitoshi Oshitani

Affiliations

Yura K Ko: 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
Yuki Furuse: 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
Kota Ninomiya: 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
Kanako Otani: Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan
Hiroki Akaba: Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575
Reiko Miyahara: Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan
Tadatsugu Imamura: 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
Takeaki Imamura: Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575
Alex R Cook: Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, 12 Science Drive 2, #10-01, Singapore
Mayuko Saito: Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575
Motoi Suzuki: Center for Surveillance, Immunization, and Epidemiologic Research, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, Japan
Hitoshi Oshitani: Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575; Corresponding author. Hitoshi Oshitani, MD, MPH, PhD, Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan 980-8575. Telephone number: +81-22-717-8211, FAX number: +81-22-717-8212.

Journal volume & issue: Vol. 116
pp. 365 – 373

Abstract

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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.

Published in International Journal of Infectious Diseases

ISSN: 1201-9712 (Print); 1878-3511 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Medicine: Internal medicine: Infectious and parasitic diseases
Website: http://www.journals.elsevier.com/international-journal-of-infectious-diseases/

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