What effect might border screening have on preventing the importation of COVID-19 compared with other infections? A modelling study

Abstract

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.

Mitigating isolation: further comparing the effect of LFD testing for early release from self-isolation for COVID-19 cases

“…Our model uses a similar Monte Carlo based structure as presented by Bays et al for use in studying border screening policies[4], [5]. The model starts by simulating 500,000 individuals, all being assumed to have become infected with COVID-19 at some point prior, each of which is then randomly assigned an infectious period (given in days), t inf , sampled from a gamma distribution (shape = 2, scale = 2.1) which has been fitted to real-time data using methods described by Birrell et al[6].…”

International Travel-Related Control Measures to contain The Covid-19 Pandemic: An update to a Cochrane Rapid Review

“…Reasons for exclusion Arino 2021 (24) The study does not provide a specific effect measure for the air travel-related control measure Bays 2021 (26) The study does not measure the specified interventions Chang 2020 (27) The study does not assess the impact of an air travel-related control measure Chen 2020 (28) The study does not measure the specified interventions Chen 2021 (29) The study does not provide a specific effect measure for an air travel-related control measure Cheng 2021 (30) The study does not assess the impact of an air travel-related control measure Chevaliera 2021 (31) The study does not provide a specific effect measure for the air travel-related control measure Chinyoka 2021 (32) The study does not measure the specified interventions Colavita 2021 (33) The study does not assess the impact of an air travel-related control measure Cowling 2020 (34) The study does not provide a specific effect measure for the air travel-related control measure Cruz-Pacheco 2020 (35) The study does not provide a specific effect measure for an air travel-related control measure Ghafari 2021 (36) The study does not measure the specified outcomes Goel 2021 (37) The study does not measure the specified outcomes Grout 2021 (38) The study does not include air travellers Haddaway 2021…”

What effect might border screening have on preventing importation of COVID-19 compared with other infections?: considering the additional effect of post-arrival isolation

“…In a recent paper [ 1 ], we described an adaptable model which could be used to assess the effectiveness of implementing a strict policy of on-arrival testing at airports during international disease outbreaks. We subsequently used this model to evaluate the probability that a single test at-point-of-arrival would be able to detect infected travellers across a range of scenarios, given that they were not detected by assumed exit screening (where evasion of exit screening was defined to occur in our model as individuals who have not fully incubated, thus being detectable to exit screening, by the time they boarded their flight).…”