WASHINGTON -- As if the COVID-19 pandemic hadn't produced enough ways to complicate life at the border between Canada and the United States, here comes another: whether or not to require proof of vaccination.

Debate is heating up in the freedom-focused U.S. about whether retailers, businesses and employers can and should require customers, workers and visitors to prove they've had a vaccine.

The discussion is also happening in Canada, a country some observers say is more attuned to the collective good than many of those in the land of life, liberty and the pursuit of happiness.

Where the two meet up, potential snafus abound.

"Some of these discussions could be very challenging," said Jack Jedwab, president of the Association for Canadian Studies and the Canadian Institute for Identities and Migration.

"I don't think that Canadians are going to look kindly on the idea that, you know, you could have significant numbers of people crossing the border that are unvaccinated."

That could be part of the reason for the apparent difference of opinion that emerged Tuesday between Ottawa and the White House on the issue of requiring vaccine documentation.

"The government is not now, nor will we be, supporting a system that requires Americans to carry a credential," press secretary Jen Psaki told the daily White House briefing.

The priority for the White House will be to protect the "privacy and rights" of U.S. residents "so that these systems are not used against people unfairly," she said.

"There will be no federal vaccinations database and no federal mandate requiring everyone to obtain a single vaccination credential."

Contrast that with Prime Minister Justin Trudeau, who -- all the while couching his response in familiar too-soon caveats -- appeared receptive to the idea of vaccine-related travel documents.

"We will continue to work with our partners in the United States and internationally to ensure that this is done properly," Trudeau said in French about how best to reopen the Canada-U.S. border.

"We have already seen the importance of proof of vaccination for international travel ... in a pre-pandemic period in recent years. It will surely be important, but the details of what we are going to do about it, we are still fine-tuning."

A new online Leger poll, commissioned by Jedwab's ACS and the Canadian Institute for Health Research at the University of Manitoba, suggests the idea is divisive on either side of the border.

Just over half of Canadian respondents, 52 per cent, said they support showing proof of vaccination to get into events or venues, compared with 43 per cent of their U.S. counterparts.

One-third of Canadians, or 33 per cent, said they opposed the idea, compared with 36 per cent of Americans who felt the same way. In the U.S., 21 per cent said they were undecided, compared with 15 per cent in Canada.

Online surveys cannot be assigned a margin of error because they do not randomly sample the population.

Many Americans these days are predisposed to oppose anything they see as a threat to freedom, said Matthew Mitchell, a professor of international business and strategy at Drake University in Des Moines, Iowa.

"I think with the rise of the don't-tread-on-me ethos, especially within the last 10 years, any infringement on individual liberties is viewed with suspicion, is viewed with antagonism," Mitchell said.

The country's famous political polarization hasn't helped.

Texas Gov. Greg Abbott, a Republican who last month lifted all COVID-19 restrictions in his state, signed an executive order Tuesday prohibiting the use of "vaccine passports" issued by the government.

"Don't tread on our personal freedoms," he tweeted.

The move follows a similar decision last week by another prominent Republican, lockdown opponent and outspoken Donald Trump ally, Florida Gov. Ron DeSantis.

"Vaccine passports reduce individual freedom and will harm patient privacy," said the order signed by DeSantis.

What was initially a come-one, come-all approach to vaccines in Florida -- later tempered to require at least some proof of temporary residency -- has been attracting older visitors from Canada for months.

Interest has spiked again as Canadians confront a four-month wait between doses of the vaccine, a delay travel insurance specialist Martin Firestone said many of his clients simply aren't willing to endure.

"All of a sudden, a new spate of calls from people saying, 'This is crazy,"' Firestone said -- in many cases, from clients who have already had their initial shot.

Once they're immunized, they're learning that getting the vaccine doesn't afford them any latitude in Canada, whether it's from insurance companies or the federal quarantine requirements for travellers.

"At this point, government and insurance companies are not recognizing at all that you've had any vaccine, and don't care to see any proof of it," Firestone said.

"Canada is just a basically turning a blind eye ... and you're not getting any credit, if that's a good word, for having both vaccines."

Fully vaccinated travellers do not have to be tested before leaving the U.S. unless a test is required at the destination, and self-quarantine upon returning home is also not required, the U.S. Centers for Disease Control says.

U.S. citizens, including those who are fully vaccinated, do require a negative COVID-19 test result no more than three days before boarding a flight home.

"What will happen in the future?" asked Firestone. "That's a great question -- that will be the precursor to the vaccine passport, that we need to see proof that you've had the vaccine."

This report by The Canadian Press was first published April 7, 2021.