Eilersen Andreas, Bjørnstad Ottar N, Li Ruiyun, Schreiber Sebastian J, Pei Zeyuan, Stenseth Nils Chr
Theoretical Biology Group, Department of Environmental Systems Science, ETH Zürich, Zürich 8092, Switzerland.
PandemiX Center, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark.
Proc Natl Acad Sci U S A. 2025 Mar 25;122(12):e2418170122. doi: 10.1073/pnas.2418170122. Epub 2025 Mar 18.
To understand infectious disease dynamics, we need to understand the inextricably intertwined nature of the ecology and evolution of pathogens and hosts. Epidemiological dynamics of many infectious diseases have highlighted the importance of considering the demographics of the societies in which they spread, particularly with respect to age structure. In addition, the waves of the recent COVID-19 pandemic driven by variant replacements at an unprecedented speed show that it is vital to consider the evolutionary aspects. The classic trade-off theory of virulence addresses aspects of pathogen evolution, but here we explore in more detail the possibility of society-specific evolutionarily stable strategies (ESS) during an unfolding pandemic. Theory posits the existence under some conditions of an ESS representing the evolutionary endpoint of change. By using a demographically realistic model incorporating infection rates that vary with age, we outline which evolutionary scenarios are plausible. Focusing on the rate of infection and duration of infectivity, we ask whether an ESS exists, what characterizes it, and as a result which long-term public-health consequences may be expected. We demonstrate that the ESS of an evolving pathogen depends upon the background age-dependent frailty and mortality rates. Our findings shed important light on the plausible long-term trajectories of highly evolvable novel pathogens.
为了理解传染病动态，我们需要了解病原体与宿主的生态学和进化之间千丝万缕的交织本质。许多传染病的流行病学动态凸显了考虑疾病传播所在社会的人口统计学特征的重要性，尤其是年龄结构方面。此外，近期由变种以史无前例的速度更替驱动的新冠疫情浪潮表明，考虑进化方面至关重要。经典的毒力权衡理论阐述了病原体进化的一些方面，但在此我们更详细地探讨在疫情发展过程中特定于社会的进化稳定策略（ESS）的可能性。理论假定在某些条件下存在一种代表进化变化终点的ESS。通过使用一个包含随年龄变化的感染率的人口统计学现实模型，我们概述了哪些进化情景是合理的。聚焦于感染率和传染期时长，我们探讨是否存在ESS、其特征是什么，以及可能预期会有哪些长期公共卫生后果。我们证明，进化中的病原体的ESS取决于与年龄相关的脆弱性和死亡率背景。我们的研究结果为高度可进化的新型病原体可能的长期轨迹提供了重要启示。
