Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
School of Public Health, The University of Hong Kong, Hong Kong, China.
Indoor Air. 2020 Jul;30(4):645-661. doi: 10.1111/ina.12673. Epub 2020 Apr 20.
Close contact was first identified as the primary route of transmission for most respiratory infections in the early 20th century. In this review, we synthesize the existing understanding of the mechanisms of close contact transmission. We focus on two issues: the mechanism of transmission in close contact, namely the transmission of the expired particles between two people, and the physical parameters of close contact that affect the exposure of particles from one individual to another, or how the nature of close contact plays a role in transmission. We propose the existence of three sub-routes of transmission: short-range airborne, large droplets, and immediate body-surface contact. We also distinguish a "body contact," which is defined with an interpersonal distance of zero, from a close contact. We demonstrate herein that the short-range airborne sub-route may be most common. The timescales over which data should be collected to assess the transmission risk during close contact events are much shorter than those required for the distant airborne or fomite routes. The current paucity of high-resolution data over short distances and timescales makes it very difficult to assess the risk of infection in these circumstances.
早在 20 世纪初，密切接触就被首次确定为大多数呼吸道传染病的主要传播途径。在这篇综述中，我们综合了目前对密切接触传播机制的理解。我们重点关注两个问题：密切接触中的传播机制，即两个人之间呼出颗粒的传播，以及影响颗粒从一个人暴露到另一个人身上的密切接触的物理参数，或者密切接触的性质如何在传播中发挥作用。我们提出了三种传播途径：短程空气传播、大飞沫和直接的体表接触。我们还将人际距离为零的“身体接触”与密切接触区分开来。我们在此证明，短程空气传播途径可能最为常见。与远距离空气传播或媒介传播途径相比，评估密切接触事件期间传播风险所需收集数据的时间尺度要短得多。目前，在短距离和短时间尺度上缺乏高分辨率数据，使得评估这些情况下的感染风险变得非常困难。
