The Canadian prime minister, Justin Trudeau, speaks during a news conference on the Covid-19 situation from his residence in Ottawa where he is self-isolating on Monday. Photograph: Dave Chan/AFP via Getty Images Canada has closed its borders to all foreign nationals except for US citizens, as the country’s prime minister unveiled “increasingly aggressive” measures to contain the new coronavirus outbreak, and urged people to stay at home. “Over the past few days, we’ve seen Covid-19 spread around the world at an even faster pace. Canada is no exception,” Trudeau, speaking from outside his home where he is in self-imposed quarantine after his wife, Sophie Grégoire Trudeau tested positive for the virus last week. “We assured you that as the situation evolved, our response would evolve too as the virus continues it spread. We’ve decided to take increasingly aggressive steps to keep you and your family safe. “All Canadians as much as possible should stay home,” he said. Trudeau said the borders will remain open for shipping, but said his government will restrict flights to Canada to airports in four major cities: Toronto Pearson, Montreal-Trudeau, Vancouver international and Calgary international. The move to close its borders contrasts with previous comments from the country’s health minister, Patty Hajdu, who rejected the idea on Friday. But in recent days, Canada has experienced a surge in cases, prompting the country’s chief public health officer, Theresa Tam, to warn residents that the chance to prevent the healthcare system from becoming overwhelmed is closing fast. Covid-19 outbreak: what do health experts mean by "flattening the curve"? Read more “Our window to flatten the curve of the epidemic is narrow,” Tam said over the weekend. “We all need to act now. Covid-19 is a serious public health threat.” Canada now has 377 confirmed cases of the coronavirus – more than double Friday’s figures. On Monday morning, the province of Ontario announced 17 testing sites and a C$10m (US$7.2m) public awareness campaign, as well as emergency legislation that would bar companies from laying off employees who have to self-quarantine. Advertisement “We’re facing rough waters ahead,” the premier, Doug Ford, told reporters. “We will get through this together.” His government also plans to include protections for parents at home caring for children. The province announced 32 new cases, bringing the provincial total to 177 – making it the region with the highest concentration of infections. “[The law] will be in place until this disease is defeated” said the province’s minister of labour, Monte McNaughton. “People who are infected should be able to do the right thing.” Over the weekend, the province of Alberta chose to shut down all public schools, joining a number of other provinces that have previously announced closures – and warning that the schools may stay closed for the rest of the academic year. “This pandemic will not end in a matter of weeks, and there won’t be a clear opportunity to reopen schools, likely not until September at the earliest,” said the province’s chief medical officer of health, Dr Deena Hinshaw. Other provinces have taken more extreme measures. Quebec has told all bars, clubs and gyms to close and called on residents to practice social distancing and to remain at home when possible. Despite the varied responses to the outbreak across the country, Trudeau urged unity. “The strength of our country is our capacity to come together and care for each other, especially in times of need. So call your friends, check in with your family. Think of your community,” he said.