Estimation of basic reproduction numbers as an indicator of infectivity based on incomplete or indirect information

• Project/Area Number: 18K17371
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 58030:Hygiene and public health-related: excluding laboratory approach
• Research Institution: National Center for Global Health and Medicine (2019-2022); Hokkaido University (2018)
• Principal Investigator: Asai Yusuke 国立研究開発法人国立国際医療研究センター, 国際感染症センター, 研究員 (70779991)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000); Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2018: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 理論疫学 / 数理モデル / 数値シミュレーション / 感染症 / 医学統計 / 基本再生産数の推定 / 統計学的推定

Outline of Final Research Achievements

A mathematical model including time delay and diagnostic bias terms was constructed and COVID-19 data were analyzed. Infection-related parameters were estimated and the results published as an original article (doi: 10.1016/j.jiac.2020.12.011.). Using a mathematical model that describes infectious disease epidemics as differential equations and international human movement as a stochastic process, the arrival time of infected individuals in disease-free countries was estimated and the relationship with R0 was clarified (https://doi.org/10.1016/j.idm.2023.05.004). A model of infection transmission was developed that takes into account the distance between individuals. Simulations confirmed the geographical and temporal spread of infection.

Academic Significance and Societal Importance of the Research Achievements

医療政策を考える上で，データに基づいた意思決定は不可欠である．基本再生産数R0はこの判断に欠かせない指標であるが，用いられるデータが限られており，その推定が困難なケースが多く報告されてきた．
そこで本研究では，今まで用いられてこなかった間接的なデータをもとにしたR0の推定モデル・手法を構築した．構築した手法を用いて感染にかかるパラメータの推定とシミュレーションを行い，チャーター便の効果や検疫の効果を推定した．今後も新たな感染症の流行が想定される．本研究で構築したR0の推定手法やその枠組みを活用しシナリオ分析を行うことで，政策決定に必要なデータの取得と定量的な議論が可能となった．

Research Products

• [Int'l Joint Research] Auburn University(米国)
• [Journal Article] Dynamics of an SEIR model for infectious diseases in random environments (2023)
  • Author(s): Yusuke Asai, Jiaqi Cheng, Xiaoying Han
  • Journal Title: Mathematical Modelling: Theory and Application, Contemporary Mathematics, AMS Volume: -
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Effect of evacuation of Japanese residents from Wuhan, China, on preventing transmission of novel coronavirus infection: A modelling study (2021)
  • Author(s): Asai Yusuke、Tsuzuki Shinya、Kutsuna Satoshi、Hayakawa Kayoko、Ohmagari Norio
  • Journal Title: Journal of Infection and Chemotherapy Volume: 27 Issue: 3 Pages: 515-520
  • DOI: 10.1016/j.jiac.2020.12.011
  • Peer Reviewed
• [Journal Article] Numerical schemes for ordinary delay differential equations with random noise (2019)
  • Author(s): Asai Y. and Kloeden P.E.
  • Journal Title: Applied Mathematics and Computation Volume: 347 Pages: 306-318
  • DOI: 10.1016/j.amc.2018.11.033
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Mathematical analysis of a transformed ODE from a PDE multiscale model of hepatitis C virus infection (2019)
  • Author(s): Kitagawa K., Kuniya T., Nakaoka S., Asai Y., Watashi K. and Iwami S.
  • Journal Title: Bulletin of Mathematical Biology Volume: 81(5) Issue: 5 Pages: 1427-1441
  • DOI: 10.1007/s11538-018-00564-y
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Quantifying heterogeneous contact patterns in Japan: a social contact survey (2019)
  • Author(s): Lankeshwara Munasinghe, Yusuke Asai, Hiroshi Nishiura
  • Journal Title: Theoretical Biology and Medical Modelling Volume: 16:6 Pages: 1-10
  • NAID: 120006626579
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Evaluation of the effectiveness of health countermeasures against infectious disease arrival times (2023)
  • Author(s): Yusuke Asai
  • Organizer: Biomath 2023
  • Int'l Joint Research
• [Presentation] Dynamics of an SEIR model with random perturbation (2022)
  • Author(s): Yusuke Asai
  • Organizer: European Conference on Mathematical and Theoretical Biology
  • Int'l Joint Research
• [Presentation] Dynamics of SEIR model in random environment (2021)
  • Author(s): Yusuke Asai
  • Organizer: Biomath 2021
  • Int'l Joint Research
• [Presentation] Estimation of the basic reproduction number using viral sequence data and the number of reported cases (2019)
  • Author(s): Asai Yusuke
  • Organizer: CMPD5 (Fifth Conference on Computational and Mathematical population Dynamics)
  • Int'l Joint Research
• [Presentation] Dynamics of an SEIR model for infectious diseases in random environment (2019)
  • Author(s): Asai Yusuke
  • Organizer: ICIAM 2019 (International Congress on Industrial and Applied Mathematics)
  • Int'l Joint Research
• [Presentation] Dynamics of SEIR-type infectious disease model in random environment (2019)
  • Author(s): 浅井雄介
  • Organizer: 日本数理生物学会
• [Presentation] Estimation of the basic reproduction number using genome information (2018)
  • Author(s): Yusuke Asai
  • Organizer: The 77th Annual Meeting of Japanese Society of Public Health, Fukushima
  • Int'l Joint Research
• [Presentation] ランダム環境下でのジカ流行動態と数値シミュレーション (2018)
  • Author(s): 浅井雄介
  • Organizer: 第１５回生物数学の理論とその応用，RIMS共同研究，京都大学数理解析研究所
• [Presentation] Numerical methods for random ordinary differential equations with time delay (2018)
  • Author(s): Yusuke Asai
  • Organizer: The 12th AIMS Conference on Dynamical Systems, Differential Equations and Applications, Taipei, Taiwan
  • Int'l Joint Research