The shelving of the Hong Kong-Singapore travel bubble shows just how delicate the process of reopening borders is — even for places that have largely contained the coronavirus.

Asia’s virus outbreak is dwarfed by those in the U.S. and Europe, but a recent uptick in cases in Hong Kong proved enough to delay the start of the air corridor between the two financial hubs by two weeks, dashing the plans of those who booked flights that were due to begin Sunday. The bubble between Hong Kong and Singapore was heralded as a pandemic world-first, allowing people to travel to and from the two places without the need for quarantine.

"This is a sober reminder that the COVID-19 virus is still with us, and even as we fight to regain our normal lives, the journey will be full of ups and downs,” Singapore Transport Minister Ong Ye Kung said Saturday.