The impact of earlier reopening to travel in the Western Pacific on SARS-CoV-2 transmission.

Background: The COVID-19 pandemic has led to a fall of over 70% in international travel, resulting in substantial economic damages. The impact is especially pronounced in the Asia-Pacific region, where governments have been slow to relax border restrictions. Methods: A retrospective approach was used to construct notional epidemic trajectories for eight Asia-Pacific countries or regions, from June to November 2021, under hypothetical scenarios of earlier resumption of international travel and selective border reopening. The numbers of local infections and deaths over the prediction window were calculated accordingly. Results: Had quarantine-free entry been permitted for all travellers from all the regions investigated, and travel volumes recovered to the 2019 levels, Australia, New Zealand, and Singapore would have been the three most severely affected regions, with at least doubled number of deaths, while infections would have increased marginally (< 5%) for Japan, Malaysia, and Thailand. Conclusions: Earlier resumption of travel in Asia-Pacific, while maintaining a controlled degree of importation risk, could have been implemented through selective border-reopening strategies and on-arrival testing. Once countries had experienced large, localized COVID-19 outbreaks, earlier relaxation of border containment measures would not have resulted in a great increase in morbidity and mortality.