Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK.
Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry CV4 7AL, UK.
J R Soc Interface. 2020 Dec;17(173):20200540. doi: 10.1098/rsif.2020.0540. Epub 2020 Dec 9.
A key challenge for many infectious diseases is to predict the time to extinction under specific interventions. In general, this question requires the use of stochastic models which recognize the inherent individual-based, chance-driven nature of the dynamics; yet stochastic models are inherently computationally expensive, especially when parameter uncertainty also needs to be incorporated. Deterministic models are often used for prediction as they are more tractable; however, their inability to precisely reach zero infections makes forecasting extinction times problematic. Here, we study the extinction problem in deterministic models with the help of an effective 'birth-death' description of infection and recovery processes. We present a practical method to estimate the distribution, and therefore robust means and prediction intervals, of extinction times by calculating their different moments within the birth-death framework. We show that these predictions agree very well with the results of stochastic models by analysing the simplified susceptible-infected-susceptible (SIS) dynamics as well as studying an example of more complex and realistic dynamics accounting for the infection and control of African sleeping sickness ().
对于许多传染病来说,一个关键的挑战是在特定干预措施下预测灭绝时间。一般来说,这个问题需要使用随机模型,这些模型认识到动态的固有基于个体的、机会驱动的性质;然而,随机模型在计算上通常是昂贵的,尤其是当需要纳入参数不确定性时。确定性模型通常用于预测,因为它们更容易处理;然而,它们无法精确地达到零感染,这使得预测灭绝时间成为一个问题。在这里,我们借助于对感染和恢复过程的有效“出生-死亡”描述来研究确定性模型中的灭绝问题。我们提出了一种实用的方法,通过在出生-死亡框架内计算其不同的矩来估计灭绝时间的分布,从而得到稳健的均值和预测区间。我们通过分析简化的易感染-感染-易感染(SIS)动态以及研究一个更复杂和现实的动态的例子来证明这些预测与随机模型的结果非常吻合,该例子考虑了非洲昏睡病的感染和控制。