Optimal vaccine allocation strategy: Theory and application to the early stage of COVID-19 in Japan

Toshikazu Kuniya; Taisuke Nakata; Daisuke Fujii; Toshikazu Kuniya; Taisuke Nakata; Daisuke Fujii

doi:10.3934/mbe.2024277

Mathematical Biosciences and Engineering

2024, Volume 21, Issue 6: 6359-6371. doi: 10.3934/mbe.2024277

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Research article

Optimal vaccine allocation strategy: Theory and application to the early stage of COVID-19 in Japan

1.
Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
2.
Graduate School of Economics and Graduate School of Public Policy, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
3.
Research Institute of Economy, Trade and Industry, 1-3-1, Kasumigaseki Chiyoda-ku, Tokyo 100-8901, Japan

Received: 04 January 2024 Revised: 30 April 2024 Accepted: 11 June 2024 Published: 19 June 2024

In this paper, we construct an age-structured epidemic model to analyze the optimal vaccine allocation strategy in an epidemic. We focus on two topics: the first one is the optimal vaccination interval between the first and second doses, and the second one is the optimal vaccine allocation ratio between young and elderly people. On the first topic, we show that the optimal interval tends to become longer as the relative efficacy of the first dose to the second dose (RE) increases. On the second topic, we show that the heterogeneity in the age-dependent susceptibility (HS) affects the optimal allocation ratio between young and elderly people, whereas the heterogeneity in the contact frequency among different age groups (HC) tends to affect the effectiveness of the vaccination campaign. A counterfactual simulation suggests that the epidemic wave in the summer of 2021 in Japan could have been greatly mitigated if the optimal vaccine allocation strategy had been taken.
- COVID-19,
- vaccination,
- mathematical model,
- age structure,
- optimal allocation
Citation: Toshikazu Kuniya, Taisuke Nakata, Daisuke Fujii. Optimal vaccine allocation strategy: Theory and application to the early stage of COVID-19 in Japan[J]. Mathematical Biosciences and Engineering, 2024, 21(6): 6359-6371. doi: 10.3934/mbe.2024277

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Abstract

In this paper, we construct an age-structured epidemic model to analyze the optimal vaccine allocation strategy in an epidemic. We focus on two topics: the first one is the optimal vaccination interval between the first and second doses, and the second one is the optimal vaccine allocation ratio between young and elderly people. On the first topic, we show that the optimal interval tends to become longer as the relative efficacy of the first dose to the second dose (RE) increases. On the second topic, we show that the heterogeneity in the age-dependent susceptibility (HS) affects the optimal allocation ratio between young and elderly people, whereas the heterogeneity in the contact frequency among different age groups (HC) tends to affect the effectiveness of the vaccination campaign. A counterfactual simulation suggests that the epidemic wave in the summer of 2021 in Japan could have been greatly mitigated if the optimal vaccine allocation strategy had been taken.

References

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