In this paper, we consider the impact of heterogeneous susceptibility on disease transmission dynamics, using a simple mathematical model formulated by a system of ordinary differential equations. Our model describes a time-varying immunity level, which is enhanced by reinfection and diminished by waning immunity. Through mathematical analysis, we show that unexpected outbreaks, called delayed outbreaks, occur even when the basic reproduction number is less than one. A reallocation of susceptibility at the individual level, by repeated infections, in the host population induces delayed outbreaks.

中文翻译：

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由于反复感染，流行病动态随时间变化。

在本文中，我们使用由常微分方程组建立的简单数学模型来考虑异质药敏性对疾病传播动力学的影响。我们的模型描述了随时间变化的免疫水平，通过重新感染可以增强免疫水平，而减弱的免疫能力则会降低免疫水平。通过数学分析，我们发现，即使基本复制数小于1，也会发生意外爆发，称为延迟爆发。通过反复感染，在寄主人群中个体水平的易感性重新分配会导致疾病爆发。