Non-essential travel between the U.S. and Canada will be banned for another month despite mounting pressure from businesses to ease COVID-19 travel restrictions.

Justin Trudeau’s border chief announced an extension of the current border rules until at least July 21 in a tweet Friday morning. The world’s longest undefended border has been closed to most travel since March 2020, when it was shut in an effort to stop the spread of the coronavirus.

Public Safety Minister Bill Blair also said restrictions on travel to other countries would continue, but added the Canadian government would begin to flesh out planned exemptions for fully vaccinated travelers on Monday.

“We are working on two tracks in terms of proof of vaccinations for Canadians who wish to travel,” Trudeau said at a midday video conference from his Ottawa residence. “We have to really make sure that not only fully vaccinated people can travel but that the communities to which they return are not at risk.”

Friday’s announcement comes as airlines, tour operators and other businesses plead with governments on both sides of the border to start reopening, with the vital summer season about to begin.

The prime minister, who is in quarantine after a trip to the U.K. and Brussels to attend international summits, provided some detail about the government’s plan to ease restrictions. Trudeau said the first phase is to allow fully vaccinated residents to upload proof of inoculation onto a mobile phone app that travelers are already required to use in order to enter the country. That will allow them certain exemptions to quarantine rules.

The second phase would include the creation of a national certification program that would be recognized around the world and allow Canadians to travel abroad.

“It’s disappointing because it flies in the face of science and is unfair to Canadians who are being denied the ability to travel, and it’s obviously very damaging to us economically as well,” Perrin Beatty, president of the Canadian Chamber of Commerce, said in a phone interview. “It’s another nail in the coffin for the the summer tourism season for Canadians.

The tourism industry has been one of the hardest hit sectors from the pandemic travel restrictions. The Canadian side of Niagara Falls, in Ontario, saw total visitors drop by half last year, and businesses are desperate not to lose another season.

“We welcome 14 million visitors a year, and of that 30 per cent come from the U.S. We know with the border closed, that 30 per cent has gone to zero,” Janice Thomson, president of Niagara Falls Tourism, said by phone, adding the region saw under 8 million visitors in 2020

Now that vaccines are being administered widely in both the U.S. and Canada, business groups are asking for a clear plan on how the border will reopen.

Vaccination rates are one of the key benchmarks Trudeau’s government is considering before allowing more non-essential travel. About 65 per cent of Canadians have received their first dose, according to data compiled by CTV News, while the Bloomberg Vaccine Tracker shows 53 per cent of U.S. residents have had a single shot.

Canada’s decision to prioritize first doses, however, has created a gap on full vaccinations: about 45 per cent of Americans have had two doses, compared to just 16 per cent in Canada.