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Volume 28, Number 1—January 2022
Research Letter

Effectiveness of International Travel Controls for Delaying Local Outbreaks of COVID-19

Bingyi Yang, Sheena G. Sullivan, Zhanwei Du, Tim K. Tsang, and Benjamin J. CowlingComments to Author 
Author affiliations: The University of Hong Kong, Hong Kong, China (B. Yang, Zhanwei Du, T.K. Tsang, B.J. Cowling); University of Melbourne Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia (S.G. Sullivan); Laboratory of Data Discovery for Health Limited, Hong Kong (Z. Du, B.J. Cowling)

Main Article

Table

Estimated time ratios and hazard ratios for comparing selected outcomes in countries that did and did not implement international controls before identifying their first cases of COVID-19, January–July 2020*

Endpoint Adjusted time ratio (95% CI)†
Adjusted hazard ratio (95% CI)‡
Any international controls The strongest international controls Any international controls The strongest international controls
Case peak 1.22 (1.06–1.41) 1.31 (1.02–1.68) 0.66 (0.46–0.93) 0.65 (0.39–1.08)
Death peak
1.23 (1.01–1.51)
0.98 (0.71–1.37)

0.74 (0.53–1.04)
0.90 (0.53–1.55)
Cumulative incidence, no. cases/10,000 population
0.2 1.20 (1.10–1.31) 1.23 (1.05–1.44) 0.55 (0.38–0.78) 0.61 (0.35–1.04)
1.0 1.26 (1.13–1.42) 1.27 (1.04–1.55) 0.49 (0.35–0.71) 0.90 (0.53–1.51)
5.0 1.25 (1.05–1.49) 1.34 (0.99–1.82) 0.59 (0.41–0.85) 0.90 (0.54–1.51)

*AFT, accelerated failure time; COVID-19, coronavirus disease. †Estimates were obtained from accelerated failure time models with log-logistic distribution, adjusted for population density and the strictest level of each nonpharmaceutical intervention used during the study period for each country. The 2 columns show time ratio of implementing international controls before the country’s first COVID-19 case to that after the country’s first case. ‡Estimates were obtained from Cox proportional hazard models, which adjusted for population density and time-varying nonpharmaceutical interventions during the study period for each country. The 2 columns show hazard ratio of implementing international controls before the country’s first COVID-19 case to that after the country’s first case.

Main Article

Page created: October 13, 2021
Page updated: October 13, 2021
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