Abell Isobel R, McCaw James M, Baker Christopher M
School of Mathematics and Statistics, The University of Melbourne, Melbourne, Australia.
Melbourne Centre for Data Science, The University of Melbourne, Melbourne, Australia.
Infect Dis Model. 2023 May 22;8(2):539-550. doi: 10.1016/j.idm.2023.05.003. eCollection 2023 Jun.
Vaccination is an important epidemic intervention strategy. However, it is generally unclear how the outcomes of different vaccine strategies change depending on population characteristics, vaccine mechanisms and allocation objective. In this paper we develop a conceptual mathematical model to simulate strategies for pre-epidemic vaccination. We extend the SEIR model to incorporate a range of vaccine mechanisms and disease characteristics. We then compare the outcomes of optimal and suboptimal vaccination strategies for three public health objectives (total infections, total symptomatic infections and total deaths) using numerical optimisation. Our comparison shows that the difference in outcomes between vaccinating optimally and suboptimally depends on vaccine mechanisms, disease characteristics, and objective considered. Our modelling finds vaccines that impact transmission produce better outcomes as transmission is reduced for all strategies. For vaccines that impact the likelihood of symptomatic disease or dying due to infection, the improvement in outcome as we decrease these variables is dependent on the strategy implemented. Through a principled model-based process, this work highlights the importance of designing effective vaccine allocation strategies. We conclude that efficient allocation of resources can be just as crucial to the success of a vaccination strategy as the vaccine effectiveness and/or amount of vaccines available.
疫苗接种是一项重要的疫情干预策略。然而，不同疫苗策略的效果如何随人群特征、疫苗作用机制和分配目标而变化，通常尚不清楚。在本文中，我们构建了一个概念性数学模型来模拟疫情前疫苗接种策略。我们扩展了SEIR模型，纳入了一系列疫苗作用机制和疾病特征。然后，我们使用数值优化方法，比较了针对三个公共卫生目标（总感染数、总症状性感染数和总死亡数）的最优和次优疫苗接种策略的效果。我们的比较表明，最优接种和次优接种在效果上的差异取决于疫苗作用机制、疾病特征以及所考虑的目标。我们的模型发现，随着所有策略的传播率降低，影响传播的疫苗会产生更好的效果。对于影响出现症状性疾病或因感染而死亡可能性的疫苗，随着我们降低这些变量，效果的改善取决于所实施的策略。通过基于模型的严谨过程，这项工作突出了设计有效疫苗分配策略的重要性。我们得出结论，资源的有效分配对于疫苗接种策略的成功可能与疫苗效力和/或可用疫苗数量同样关键。
