Border closure for island nations? Analysis of pandemic and bioweapon‐related threats suggests some scenarios warrant drastic action

Abstract

The risk to human populations from new and pandemic infectious agents has probably never been higher.1,2 Synthetic bioweapons are an additional threat. Two recent publications have speculated on the possibility of island nation refuges closing their borders to protect a human population against a catastrophic pandemic that poses an existential risk to humanity.3,4 The most recent paper described an index based on characteristics of an island nation’s population, location, resources and society. The authors used this index to conclude that Australia and New Zealand are the island nations most likely to be able to be both isolated from the rest of humanity in a pandemic and to also have the resources to reboot a thriving technological society following a pandemic that devastated the rest of global society as we know it, thereby acting as ‘island refuges’.4 Previous analysis in this journal has argued the economic case for border closure by island nations in the face of extreme pandemics.5 This work reported that 100 per cent border closure for six months by New Zealand, that results in the country avoiding any pandemic cases, could have a net present value of NZ$7.86 (US$5.29) billion for its “Scenario A” (involving half the mortality rate of the 1918 influenza pandemic) and NZ$144 (US$96.9) billion for preventing a pandemic with 10 times this mortality. There is evidence for travel restrictions being successful in controlling the spread of influenza between countries, and small islands successfully used protective sequestration and maritime quarantine to avoid the 1918–1919 influenza pandemic ). However, the 1918- 19 pandemic still appeared to reach most of the world’s islands. Drastic measures such as border closure have potentially large benefits (if successful) but also potentially major harmful consequences including economic harm. Some of these potential trade-offs are illustrated by the 2014 Ebola outbreak where the GDP of countries affected fell by 12% during the emergency even without successful complete border closures. The question remains, which pandemics, if any, might ever plausibly justify partitioning a segment of the human population through border closure by island nations to reduce major burdens of morbidity and mortality? It is this question we address in the present commentary.