Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study

Objectives: To reconstruct age-structured case counts of COVID-19 using sentinel reporting, which replaced universal reporting of COVID-19 from May 2023 in Japan. Methods: Using COVID-19 sentinel data stratified by discrete age groups in selected prefectures and referring to universal case count dat...

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Main Authors: Yuta Okada, Minami Ueda, Hiroshi Nishiura
Format: Article
Language:English
Published: Elsevier 2024-11-01
Series:International Journal of Infectious Diseases
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Online Access:http://www.sciencedirect.com/science/article/pii/S1201971224002947
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author Yuta Okada
Minami Ueda
Hiroshi Nishiura
author_facet Yuta Okada
Minami Ueda
Hiroshi Nishiura
author_sort Yuta Okada
collection DOAJ
description Objectives: To reconstruct age-structured case counts of COVID-19 using sentinel reporting, which replaced universal reporting of COVID-19 from May 2023 in Japan. Methods: Using COVID-19 sentinel data stratified by discrete age groups in selected prefectures and referring to universal case count data up to May 8, 2023, we fitted a statistical model to handle weekly growth rates as a function of age and time so as to convert sentinel data to case counts after cessation of universal reporting. Results: The age distribution of cases in sentinel reporting was significantly biased toward younger age groups compared to universal reporting. When comparing the epidemic size of the 9th wave (May 8 to September 18, 2023) to the 8th wave (October 3, 2022 to April 10, 2023), using the wave-on-wave ratio of total cumulative sentinel cases led to a significant underestimation of the wave-on-wave in Tokyo (0.975, vs 1.461 by universal reporting) and Okinawa (1.299, vs 1.472). The estimates of growth rates, scaling factors between universal and sentinel cases, and expected universal case count showed robustness to changes in the ending week of the data period. Conclusion: Our model quantified COVID-19 dynamics, comparably to universal reporting that ended in May 2023, enabling detailed and up-to-date health burden analysis using sentinel reports. The cumulative incidence was greater than that suggested from sentinel data in Tokyo, Nara, and Okinawa. Per-population burdens among children were particularly high in Osaka and Nara, indicating a strong bias in sentinel reporting toward pediatric cases.
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spelling doaj-art-73df11752e9e450c8ba91ef9e91e5cfb2025-08-20T02:11:37ZengElsevierInternational Journal of Infectious Diseases1201-97122024-11-0114810722310.1016/j.ijid.2024.107223Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling studyYuta Okada0Minami Ueda1Hiroshi Nishiura2Graduate School of Medicine, Kyoto University, Kyoto, JapanGraduate School of Medicine, Kyoto University, Kyoto, JapanCorrespondence to: Hiroshi Nishiura, Graduate School of Medicine, Kyoto University, Yoshidakonoecho, Sakyoku, Kyoto city, Kyoto 6068503, Japan, Tel: +81-75-753-4456; fax: +81-75-753-4458.; Graduate School of Medicine, Kyoto University, Kyoto, JapanObjectives: To reconstruct age-structured case counts of COVID-19 using sentinel reporting, which replaced universal reporting of COVID-19 from May 2023 in Japan. Methods: Using COVID-19 sentinel data stratified by discrete age groups in selected prefectures and referring to universal case count data up to May 8, 2023, we fitted a statistical model to handle weekly growth rates as a function of age and time so as to convert sentinel data to case counts after cessation of universal reporting. Results: The age distribution of cases in sentinel reporting was significantly biased toward younger age groups compared to universal reporting. When comparing the epidemic size of the 9th wave (May 8 to September 18, 2023) to the 8th wave (October 3, 2022 to April 10, 2023), using the wave-on-wave ratio of total cumulative sentinel cases led to a significant underestimation of the wave-on-wave in Tokyo (0.975, vs 1.461 by universal reporting) and Okinawa (1.299, vs 1.472). The estimates of growth rates, scaling factors between universal and sentinel cases, and expected universal case count showed robustness to changes in the ending week of the data period. Conclusion: Our model quantified COVID-19 dynamics, comparably to universal reporting that ended in May 2023, enabling detailed and up-to-date health burden analysis using sentinel reports. The cumulative incidence was greater than that suggested from sentinel data in Tokyo, Nara, and Okinawa. Per-population burdens among children were particularly high in Osaka and Nara, indicating a strong bias in sentinel reporting toward pediatric cases.http://www.sciencedirect.com/science/article/pii/S1201971224002947COVID-19Sentinel surveillanceEpidemic sizeTime-series analysisJapan
spellingShingle Yuta Okada
Minami Ueda
Hiroshi Nishiura
Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
International Journal of Infectious Diseases
COVID-19
Sentinel surveillance
Epidemic size
Time-series analysis
Japan
title Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
title_full Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
title_fullStr Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
title_full_unstemmed Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
title_short Reconstructing the age-structured case count of COVID-19 from sentinel surveillance data in Japan: A modeling study
title_sort reconstructing the age structured case count of covid 19 from sentinel surveillance data in japan a modeling study
topic COVID-19
Sentinel surveillance
Epidemic size
Time-series analysis
Japan
url http://www.sciencedirect.com/science/article/pii/S1201971224002947
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