Clinical Report: Retrospective Analysis of Travel Limitations Implemented in Japan

Overview

This study retrospectively evaluated the impact of reduced international travel volume during COVID-19 travel restrictions in Japan from 2020 through 2022 on imported SARS-CoV-2 infections. Using airport entry-screening data and counterfactual travel-volume scenarios, the investigators estimated how many imported infections may have been avoided as international travel declined.

Background

Travel restrictions became a critical public health measure during the COVID-19 pandemic, with many countries implementing various interventions to control the spread of the virus. Japan's approach included strict entry policies and universal screening for travelers. Understanding the effectiveness of these measures is essential for future public health strategies.

Data Highlights

• Approximately 1.0 million border entries were observed in Japan from October 2020 through May 2022.

• Under the 3-year mean counterfactual scenario, approximately 49.5 million border entries were estimated for the same period.

• This corresponded to an estimated reduction of approximately 48.5 million entries, or about 98%.

• Depending on the counterfactual model used, reduced travel volume was associated with an estimated 536,331 to 619,327 fewer imported SARS-CoV-2 infections; the authors summarize this as approximately 530,000 to 620,000 fewer imported infections.

• The Western Pacific Region accounted for the largest estimated reduction in imported infections.

• The largest estimated monthly difference in imported infections occurred around the emergence of the Omicron variant, with January 2022 showing the highest global estimate.

Key Findings

• Japan began implementing COVID-19 travel restrictions in February 2020, initially refusing entry to certain travelers linked to Hubei Province, China.

• By early April 2020, travelers from 73 countries were subject to entry refusal.

• All travelers entering Japan were screened and tested for SARS-CoV-2 from January 9, 2021, through May 31, 2022.

• Approximately 1.0 million border entries were observed from October 2020 through May 2022, compared with approximately 49.5 million under the 3-year mean counterfactual scenario.

• Under the assumption that infection risk among travelers was identical in the observed and counterfactual scenarios, reduced travel volume was associated with an estimated 530,000 to 620,000 fewer imported infections.

• The largest estimated reduction in imported infections was associated with travel from the Western Pacific Region.

Clinical Implications

The findings quantify the potential public health impact associated with substantially reduced international travel volume during the COVID-19 pandemic. The authors emphasize that decisions about travel restrictions should consider their potential public health benefits alongside negative socioeconomic effects and interference with freedom of movement.

Conclusion

Reduced international travel volume in Japan from October 2020 through May 2022 was associated with an estimated 530,000 to 620,000 fewer imported SARS-CoV-2 infections than under counterfactual travel-volume scenarios. The estimates reflect the overall reduction in travel volume and cannot be attributed entirely to specific travel-restriction policies.

Related Resources & Content

1. Anzai A, Nishiura H. Post-hoc evaluation of travel restrictions during the COVID-19 pandemic in Japan, 2020-2022. International Journal of Infectious Diseases. 2026;171:109068.

2. Movsisyan A, Burns J, Biallas R, et al. Travel-related control measures to contain the COVID-19 pandemic: an evidence map. BMJ Open. 2021;11:e041619.

3. Burns J, Movsisyan A, Stratil JM, et al. International travel-related control measures to contain the COVID-19 pandemic: a rapid review. Cochrane Database Syst Rev. 2021;3:CD013717.

4. Klinger C, Burns J, Movsisyan A, et al. Unintended health and societal consequences of international travel measures during the COVID-19 pandemic: a scoping review. J Travel Med. 2021;28:1-17.