Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Nakhon Ratchasima, Thailand.
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
Malar J. 2021 Apr 17;20(1):189. doi: 10.1186/s12936-021-03726-x.
Many public health interventions lead to disruption or decrease of transmission, providing a beneficial effect for people in the population regardless of whether or not they individually participate in the intervention. This protective benefit has been referred to as a herd or community effect and is dependent on sufficient population participation. In practice, public health interventions are implemented at different spatial scales (i.e., at the village, district, or provincial level). Populations, however defined (i.e., neighbourhoods, villages, districts) are frequently connected to other populations through human movement or travel, and this connectedness can influence potential herd effects.
The impact of a public health intervention (mass drug administration for malaria) was modelled, for different levels of connectedness between populations that have similar disease epidemiology (e.g., two nearby villages which have similar baseline malaria incidences and similar malaria intervention measures), or between populations of varying disease epidemiology (e.g., two nearby villages which have different baseline malaria incidences and/or malaria intervention measures).
The overall impact of the interventions deployed could be influenced either positively (adding value to the intervention) or negatively (reducing the impact of the intervention) by how much the intervention units are connected with each other (e.g., how frequent people go to the other village or town) and how different the disease intensity between them are. This phenomenon is termed the "assembly effect", and it is a meta-population version of the more commonly understood "herd effect".
The connectedness of intervention units or populations is an important factor to be considered to achieve success in public health interventions that could provide herd effects. Appreciating the assembly effect can improve the cost-effective strategies for global disease elimination projects.
许多公共卫生干预措施会导致传播中断或减少，从而为人群中的所有人带来有益影响，而无论他们个人是否参与干预措施。这种保护效益被称为群体或社区效应，取决于足够的人群参与。实际上，公共卫生干预措施是在不同的空间尺度上实施的（即，在村庄、地区或省级水平）。然而，无论如何定义人群（即，邻里、村庄、地区），它们通常通过人员流动或旅行与其他人群相连，这种连通性会影响潜在的群体效应。
模拟了一种公共卫生干预措施（大规模药物治疗疟疾）的影响，对于具有相似疾病流行病学的人群（例如，两个基线疟疾发病率和类似疟疾干预措施相似的邻近村庄）或具有不同疾病流行病学的人群（例如，两个基线疟疾发病率和/或疟疾干预措施不同的邻近村庄）之间的人群，不同的连通程度对干预效果的影响。
干预措施的总体效果可能会受到干预单位之间相互连接程度的影响（例如，人们去另一个村庄或城镇的频率）以及它们之间疾病强度的差异如何，从而产生积极影响（增加干预的价值）或消极影响（降低干预的效果）。这种现象被称为“组装效应”，它是更常见的“群体效应”的元种群版本。
干预单位或人群的连通性是实现提供群体效应的公共卫生干预措施成功的一个重要因素。了解组装效应可以改善全球疾病消除项目的成本效益策略。
