Border Restriction as a Public Health Measureto Limit Outbreak of Coronavirus Disease 2019 (COVID-19)

Kwok, W. C.; Wong, C. K.; Ma, T. F.; Ho, K. W.; Fan, W. T. L.; Chan, K. P. F.; Chan, S. K. S.; Tam, C. C. T.; Ho, P. L.

Background: Coronavirus Disease 2019 (COVID-19) led to pandemic that affected almost all countries in the world. Many countries have implemented border restriction as a public health measure to limit local outbreak. However, there is inadequate scientific data to support such a practice, especially in the presence of an established local transmission of the disease. Method: A novel metapopulation Susceptible-Exposed-Infectious-Recovered (SEIR) model with inspected migration was applied to investigate the effect of border restriction between Hong Kong and mainland China on the epidemiological characteristics of COVID-19 in Hong Kong. Isolation facilities occupancy was also studied. Results: At R0 of 2.2, the cumulative COVID-19 cases in Hong Kong can be reduced by 13.99% (from 29,163 to 25,084) with complete border closure. At an in-patient mortality of 1.4%, the number of deaths can be reduced from 408 to 351 (57 lives saved). However, border closure alone was insufficient to prevent full occupancy of isolation facilities in Hong Kong; effective public health measures to reduce local R0 to below 1.6 was necessary. Conclusion: As a public health measure to tackle COVID-19, border restriction is effective in reducing cumulative cases and mortality.