标题： 疫情传播：将接触限制在固定圈子内未必是最安全的选择 显示英文标题

标题： Epidemic spread: limiting contacts to regular circles is not necessarily the safest option

摘要： 当一种新传染病（或现有传染病的新毒株）出现时，如最近的新冠疫情，会考虑采取不同类型的流动限制措施，以减缓或减轻疾病的传播。 所需的措施需要仔细权衡社会成本与其对疾病控制的影响。 在本研究中，我们在流动限制的背景下，分析了频繁接触与偶尔接触在疫情传播中的作用。 我们开发了一个基于个体的数学模型，其中考虑了个体之间的频繁接触（在家、工作、学校等）和偶尔接触（在商店、交通工具等）。 我们通过改变频繁接触和偶尔接触之间的相对权重，同时保持相同的初始有效传播率，定义了几种接触结构。 我们发现一个显著的结果：频繁接触占主导地位时，疫情高峰更高，出现得更早，受疫情影响的个体总数也更大。 我们使用SIR模型进行研究，考虑了感染后的指数恢复和确定性恢复，并发现这种效应在确定性恢复下更为明显。 我们发现，放松措施的影响取决于所考虑的社会结构中频繁接触和偶尔接触的相对重要性。 最后，我们评估了在所考虑的哪种情景中，均匀混合近似能够合理描述疫情动态。 显示英文摘要

摘要： When a new infectious disease (or a new strain of an existing one) emerges, as in the recent COVID-19 pandemic, different types of mobility restrictions are considered to slow down or mitigate the spread of the disease. The measures to be adopted require carefully weighing the social cost against their impact on disease control. In this work, we analyze, in a context of mobility restrictions, the role of frequent versus occasional contacts in epidemic spread. We develop an individual-based mathematical model where frequent contacts among individuals (at home, work, schools) and occasional contacts (at stores, transport, etc.) are considered. We define several contact structures by changing the relative weight between frequent and occasional contacts while keeping the same initial effective rate of spread. We find the remarkable result that the more frequent contacts prevail over occasional ones, the higher the epidemic peak, the sooner it occurs, and the greater the final number of individuals affected by the epidemic. We conduct our study using an SIR model, considering both exponential and deterministic recovery from infection, and obtain that this effect is more pronounced under deterministic recovery. We find that the impact of relaxation measures depends on the relative importance of frequent and occasional contacts within the considered social structures. Finally, we assess in which of the considered scenarios the homogeneous mixing approximation provides a reasonable description of the epidemic dynamics.