Volume 28, Number 1—January 2022
Research Letter
Effectiveness of International Travel Controls for Delaying Local Outbreaks of COVID-19
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.