Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023

Background: The spread of coronavirus disease 2019 (COVID-19) varied among countries. The spatiotemporal trends of COVID-19 in Japan remain understudied. Therefore, this study aimed to conduct a detailed investigation of the spatiotemporal evolution of infections/deaths across prefectures in Japan,...

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Main Authors: Atsuna Tokumoto, Kazuaki Jindai, Tomoki Nakaya, Mayuko Saito, Clive E. Sabel, Hitoshi Oshitani
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Journal of Infection and Public Health
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Online Access:http://www.sciencedirect.com/science/article/pii/S187603412500053X
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author Atsuna Tokumoto
Kazuaki Jindai
Tomoki Nakaya
Mayuko Saito
Clive E. Sabel
Hitoshi Oshitani
author_facet Atsuna Tokumoto
Kazuaki Jindai
Tomoki Nakaya
Mayuko Saito
Clive E. Sabel
Hitoshi Oshitani
author_sort Atsuna Tokumoto
collection DOAJ
description Background: The spread of coronavirus disease 2019 (COVID-19) varied among countries. The spatiotemporal trends of COVID-19 in Japan remain understudied. Therefore, this study aimed to conduct a detailed investigation of the spatiotemporal evolution of infections/deaths across prefectures in Japan, to analyze the changing patterns of COVID-19 circulation in metropolitan and nonmetropolitan areas. Methods: We extracted data from nationally represented open-source data from January 15, 2020, to May 9, 2023, and we calculated the incidence rate of infection and the mortality. Further the ratios were obtained by dividing those rates in prefectural level by those in national level to make them comparable across country. Then, the spatiotemporal trends of COVID-19 were depicted via heatmaps. A Poisson regression model was used to compare the incidence rate ratios (IRRs) of infection and death between nonmetropolitan and metropolitan prefectures. Results: During the study period, Japan experienced eight waves of COVID-19 resulting in 33,738,398 confirmed infections and 74,688 deaths. Both infections and deaths increased significantly overtime. Transmission was initially concentrated in metropolitan prefectures. Nonmetropolitan prefectures were protected and had lower numbers of infections and deaths through June 2022. Thereafter, COVID-19 became more widespread, with more localized surges in nonmetropolitan prefectures. Eventually, during the eighth wave (October 16, 2022-May 9, 2023), there was a marked increase in the IRR in nonmetropolitan prefectures reaching 1.25 (95 % confidence interval (CI), 1.15–1.34) for infection and 1.38 (95 % CI, 1.16–1.65) for death. Conclusions: In Japan, COVID-19 transmission was suppressed for the first 2 years of the pandemic, especially in nonmetropolitan prefectures, but the trends changed over time, and more infections and deaths were observed from late 2022 in nonmetropolitan prefectures. These findings underscore the importance of addressing the geographical disparities that likely exist between metropolitan and nonmetropolitan prefectures Delaying large surges in nonmetropolitan prefectures may be an important takeaway that could aid in the future management of major infectious disease outbreaks.
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spelling doaj-art-2eb231524d9d4cccb330bb26bc3768c72025-08-20T03:08:24ZengElsevierJournal of Infection and Public Health1876-03412025-05-0118510270410.1016/j.jiph.2025.102704Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023Atsuna Tokumoto0Kazuaki Jindai1Tomoki Nakaya2Mayuko Saito3Clive E. Sabel4Hitoshi Oshitani5Department of Public Health, Institute of Science Tokyo, Tokyo, Japan; Department of Pediatrics, JA Toride Medical Center, Ibaraki, JapanDepartment of Virology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, JapanGraduate School of Environmental Studies, Tohoku University, Sendai, Miyagi, Japan; Department of Earth Science, Graduate School of Science, Tohoku University, Sendai, Miyagi, JapanDepartment of Virology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, JapanSchool of Geography, Earth and Environmental Sciences, University of Plymouth, Plymouth, United KingdomDepartment of Virology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan; Correspondence to: Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.Background: The spread of coronavirus disease 2019 (COVID-19) varied among countries. The spatiotemporal trends of COVID-19 in Japan remain understudied. Therefore, this study aimed to conduct a detailed investigation of the spatiotemporal evolution of infections/deaths across prefectures in Japan, to analyze the changing patterns of COVID-19 circulation in metropolitan and nonmetropolitan areas. Methods: We extracted data from nationally represented open-source data from January 15, 2020, to May 9, 2023, and we calculated the incidence rate of infection and the mortality. Further the ratios were obtained by dividing those rates in prefectural level by those in national level to make them comparable across country. Then, the spatiotemporal trends of COVID-19 were depicted via heatmaps. A Poisson regression model was used to compare the incidence rate ratios (IRRs) of infection and death between nonmetropolitan and metropolitan prefectures. Results: During the study period, Japan experienced eight waves of COVID-19 resulting in 33,738,398 confirmed infections and 74,688 deaths. Both infections and deaths increased significantly overtime. Transmission was initially concentrated in metropolitan prefectures. Nonmetropolitan prefectures were protected and had lower numbers of infections and deaths through June 2022. Thereafter, COVID-19 became more widespread, with more localized surges in nonmetropolitan prefectures. Eventually, during the eighth wave (October 16, 2022-May 9, 2023), there was a marked increase in the IRR in nonmetropolitan prefectures reaching 1.25 (95 % confidence interval (CI), 1.15–1.34) for infection and 1.38 (95 % CI, 1.16–1.65) for death. Conclusions: In Japan, COVID-19 transmission was suppressed for the first 2 years of the pandemic, especially in nonmetropolitan prefectures, but the trends changed over time, and more infections and deaths were observed from late 2022 in nonmetropolitan prefectures. These findings underscore the importance of addressing the geographical disparities that likely exist between metropolitan and nonmetropolitan prefectures Delaying large surges in nonmetropolitan prefectures may be an important takeaway that could aid in the future management of major infectious disease outbreaks.http://www.sciencedirect.com/science/article/pii/S187603412500053XCOVID-19Spatiotemporal trendMetropolitanNonmetropolitanIncidenceMortality
spellingShingle Atsuna Tokumoto
Kazuaki Jindai
Tomoki Nakaya
Mayuko Saito
Clive E. Sabel
Hitoshi Oshitani
Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
Journal of Infection and Public Health
COVID-19
Spatiotemporal trend
Metropolitan
Nonmetropolitan
Incidence
Mortality
title Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
title_full Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
title_fullStr Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
title_full_unstemmed Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
title_short Changes in the spatiotemporal patterns of COVID-19 in Japan from 2020 through 2023
title_sort changes in the spatiotemporal patterns of covid 19 in japan from 2020 through 2023
topic COVID-19
Spatiotemporal trend
Metropolitan
Nonmetropolitan
Incidence
Mortality
url http://www.sciencedirect.com/science/article/pii/S187603412500053X
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