Quantitative assessment of the risk of airborne transmission of SARS-CoV-2 infection: Prospective and retrospective applications
Quantitative assessment of the risk of airborne transmission of SARS-CoV-2 infection: Prospective and retrospective applications
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DOI：
10.1016/j.envint.2020.106112
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发表时间：
2020-12-01
影响因子：
11.8
通讯作者：
Stabile, L.
中科院分区：
文献类型：
--
作者：
Buonanno, G.;Morawska, L.;Stabile, L.
空气传播是公认的传染途径；然而，很少对其进行定量评价。在SARS-CoV-2大流行期间发生的多次疫情对研究人员提出了要求，要求他们开发既能预测封闭环境中的传染（预测性评估）又能分析以前感染（回顾性评估）的方法。本研究提出了一种定量评估无症状感染SARS-CoV-2的室内微环境易感受试者个体感染风险的新方法。应用蒙特卡罗方法可以评估健康受试者受照射的风险，或者从可接受的风险出发，评估最大暴露时间。我们将建议的方法应用于四种不同的情景进行前瞻性评估，并强调，为了保证在自然通风的室内环境中暴露的受试者的可接受风险为103，暴露时间可能远低于1小时。这种最大暴露时间显然取决于受感染受试者的病毒载量释放和暴露条件；因此，较长的暴露时间估计机械通风的室内环境和较低的病毒载量排放。所提出的方法被用于对广州（中国）一家餐馆和弗农山（美国）合唱团排练中记录的疫情进行回顾性评估，结果表明，在这两种情况下，只有假设空气传播是传染的主要途径，才可以证明高发病率值是合理的。此外，我们表明，这种暴发不是由于罕见的超级传播者的存在而引起的，而是可能通过条件的共存来解释，包括排放和暴露参数，导致极有可能发生的事件，可以定义为“超级传播事件”。
Airborne transmission is a recognized pathway of contagion; however, it is rarely quantitatively evaluated. The numerous outbreaks that have occurred during the SARS-CoV-2 pandemic are putting a demand on researchers to develop approaches capable of both predicting contagion in closed environments (predictive assessment) and analyzing previous infections (retrospective assessment).This study presents a novel approach for quantitative assessment of the individual infection risk of susceptible subjects exposed in indoor microenvironments in the presence of an asymptomatic infected SARS-CoV-2 subject. The application of a Monte Carlo method allowed the risk for an exposed healthy subject to be evaluated or, starting from an acceptable risk, the maximum exposure time. We applied the proposed approach to four distinct scenarios for a prospective assessment, highlighting that, in order to guarantee an acceptable risk of 10 3 for exposed subjects in naturally ventilated indoor environments, the exposure time could be well below one hour. Such maximum exposure time clearly depends on the viral load emission of the infected subject and on the exposure conditions; thus, longer exposure times were estimated for mechanically ventilated indoor environments and lower viral load emissions. The proposed approach was used for retrospective assessment of documented outbreaks in a restaurant in Guangzhou (China) and at a choir rehearsal in Mount Vernon (USA), showing that, in both cases, the high attack rate values can be justified only assuming the airborne transmission as the main route of contagion. Moreover, we show that such outbreaks are not caused by the rare presence of a superspreader, but can be likely explained by the co-existence of conditions, including emission and exposure parameters, leading to a highly probable event, which can be defined as a "superspreading event".