Emergency Response Department, Public Health England, Porton Down, SalisburySP4 0JG, UK.
Epidemiol Infect. 2021 Nov 4;149:e238. doi: 10.1017/S0950268821002387.
The effectiveness of screening travellers during times of international disease outbreak is contentious, especially as the reduction in the risk of disease importation can be very small. Border screening typically consists of travellers being thermally scanned for signs of fever and/or completing a survey declaring any possible symptoms prior to admission to their destination country; while more thorough testing typically exists, these would generally prove more disruptive to deploy. In this paper, we describe a simple Monte Carlo based model that incorporates the epidemiology of coronavirus disease-2019 (COVID-19) to investigate the potential decrease in risk of disease importation that might be achieved by requiring travellers to undergo screening upon arrival during the current pandemic. This is a purely theoretical study to investigate the maximum impact that might be attained by deploying a test or testing programme simply at the point of entry, through which we may assess such action in the real world as a method of decreasing the risk of importation. We, therefore, assume ideal conditions such as 100% compliance among travellers and the use of a 'perfect' test. In addition to COVID-19, we also apply the presented model to simulated outbreaks of influenza, severe acute respiratory syndrome (SARS) and Ebola for comparison. Our model only considers screening implemented at airports, being the predominant method of international travel. Primary results showed that in the best-case scenario, screening at the point of entry may detect a maximum of 8.8% of travellers infected with COVID-19, compared to 34.8.%, 9.7% and 3.0% for travellers infected with influenza, SARS and Ebola respectively. While results appear to indicate that screening is more effective at preventing disease ingress when the disease in question has a shorter average incubation period, our results suggest that screening at the point of entry alone does not represent a sufficient method to adequately protect a nation from the importation of COVID-19 cases.
在国际疾病爆发期间，对旅行者进行筛查的效果存在争议，尤其是因为减少疾病输入的风险可能非常小。边境筛查通常包括对旅行者进行体温扫描，以发现发热迹象和/或在进入目的地国家之前填写一份声明任何可能症状的调查问卷；虽然存在更彻底的测试，但这些测试通常更具破坏性。在本文中，我们描述了一个简单的基于蒙特卡罗的模型，该模型结合了 2019 年冠状病毒病（COVID-19）的流行病学，以调查在当前大流行期间要求旅行者在抵达时接受筛查可能降低疾病输入风险的程度。这是一项纯粹的理论研究，旨在调查通过在入境点部署测试或测试计划可能实现的最大影响，我们可以通过这种方法评估在现实世界中作为降低输入风险的一种方法。因此，我们假设旅行者 100%遵守规定并使用“完美”的测试等理想条件。除 COVID-19 外，我们还将所提出的模型应用于模拟的流感、严重急性呼吸综合征（SARS）和埃博拉病毒爆发进行比较。我们的模型仅考虑在机场实施的筛查，这是国际旅行的主要方式。主要结果表明，在最佳情况下，入境点的筛查最多可检测到 8.8%感染 COVID-19 的旅行者，而感染流感、SARS 和埃博拉病毒的旅行者分别为 34.8%、9.7%和 3.0%。虽然结果表明，当所讨论的疾病的平均潜伏期较短时，筛查在预防疾病传入方面更为有效，但我们的结果表明，仅在入境点进行筛查并不能代表一种充分的方法来充分保护一个国家免受 COVID-19 病例的输入。
