Sustainable border control policy in the COVID-19 pandemic: A math modeling study

Abstract

Background Imported COVID-19 cases, if unchecked, can jeopardize the effort of domestic containment. We aim to find out what sustainable border control options for different entities (e.g., countries, states) exist during the reopening phases, given their own choice of domestic control measures. Methods We propose a SUIHR model, which has built-in imported risk and (1-tier) contact tracing to study the cross-border spreading and control of COVID-19. Under plausible parameter assumptions, we examine the effectiveness of border control policies, in combination with internal measures, to confine the virus and avoid reverting back to more restrictive life styles again. Results When the basic reproduction number of COVID-19 exceeds 2.5, even 100% effective contact tracing alone is not enough to contain the spreading. For an entity that has completely eliminated the virus domestically, and resumes “normal”, without mandatory institutional quarantine, even very strict border control measures combined with effective contact tracing can only delay another outbreak by 6 months. For entities employing a confining domestic control policy, non-increasing net imported cases is sufficient to remain open. Conclusions Extremely strict border control in entities, where domestic spreading is currently eliminated (e.g., China), is justifiable. However such harsh measure are not necessary for other places. Entities successfully confining the virus by internal measures can open up to similar entities without additional border controls so long as the imported risk stays non-increasing. Opening the borders to entities lacking sufficient internal control of the virus should be exercised in combination with pre-departure screening and tests upon arrival.

Reopening International Borders without Quarantine: Contact Tracing Integrated Policy against COVID-19

“…Although digital contact tracing is effective, additional containment measures are still needed to curb the pandemic. One unique feature of our model is to simulate the short-term stay of inbound travelers if the mandatory quarantine is relieved, which has been less mentioned in the discussion about reopening borders [ 16 , 34 ]. This feature can be further applied to modeling the outflow of exposed travelers before their symptom onset in another country.…”

Reopening International Borders without Quarantine: Contact Tracing Integrated Policy against COVID-19

“…Albeit the effectiveness of the digital contact tracing, additional containment measures are still needed to curb the pandemic. One unique feature of our model is to simulate the short-term stay of inbound travelers if the mandatory quarantine is relieved, which has been less mentioned by the discussion about reopening borders (Smith et al, 2021;Zhu et al, 2021). This feature can be further applied to modeling the outflow of asymptomatic travelers before their symptom onset in another country.…”

Downsizing of contact tracing during COVID-19 vaccine roll-out

“…Case importations contribute to epidemic spread when infection prevalence is low (Russell et al, 2021), and it is critical to consider how contact tracing practices should respond to the relaxation of border restrictions, in addition to the relaxation of social distancing. However, the link between case importations and the contact tracing efficiency needed to keep an outbreak under control has been little explored (Zhu et al, 2021). Finally, vaccination can clearly affect contact tracing management (Miller et al, 2020;Klinkenberg et al, 2006;Friston et al, 2021).…”