As provinces and countries begin to look towards easing coronavirus restrictions, some are taking an approach reminiscent of school days gone by: pick a best friend and stick with them.

The concept of “travel bubbles” appears to be gaining traction, with New Brunswick authorizing households to pick one other household with whom to socialize, and New Zealand and Australia reportedly weighing allowing their citizens to travel only between the two friendly countries.

READ MORE: U.S., other countries begin to slowly ease COVID-19 restrictions

Officials around the world have suggested basically any form of non-essential international travel is unlikely until at least the end of the year.

The question is how to inch those borders open slowly, and while Canada and the U.S. share closer ties than Australia and New Zealand, one infectious disease expert is warning against reopening the border with the U.S. in a similar manner.

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“The U.S. has the biggest epidemic in the world right now. It’s singular — no country has more cases, no country is less adherent to the only established method of interdicting cases,