OTTAWA -- The COVID-19 cluster that has forced New Brunswick to roll back some reopening measures is an example of the caution needed as jurisdictions across the country ease restrictions, Canada's top doctor said Thursday.

The provincial legislature abruptly adjourned a day after officials confirmed a health-care worker who had travelled outside New Brunswick had infected at least two other people in the Campbellton area upon return.

Premier Blaine Higgs has said the health-care worker was in contact with "multiple patients" over a two-week period after returning to the province without self-isolating.

The news means the Campbellton area, near the border with Quebec, will now have to return to tighter restrictions on physical distancing.

On Thursday, Canada's chief public health officer, Theresa Tam, said the New Brunswick case shows public health officials across the country are taking a cautious approach to reopening.

"I think there has always been the message in different jurisdictions that there's a flexibility in the public health system to reinstate or pull back on some of the measures as they see fit, based on their own epidemiological context, so I think that is what you are seeing in New Brunswick at this point," she said.

Meanwhile, Ontario also experienced a small setback as it reported 383 new cases of COVID-19 on Thursday, after several consecutive days of fewer than 300 new cases.

It brings the provincial total to 26,866, an increase of 1.4 per cent over the previous day. The number of tests reported also jumped to 17,615, from 15,133 the previous day.

Tam said that while much of Canada has "flattened the curve" of novel coronavirus infections, there are still a significant number of cases in vulnerable settings such as long-term care homes, as well as parts of Ontario and Quebec.

Prime Minister Justin Trudeau did not hold his usual COVID-19 news conference, as he co-hosted a major United Nations conference and prepared for a Thursday evening first ministers meeting.

Canada is competing for one of two non-permanent seats on the UN Security Council next month, and Trudeau is running on a platform of trying to help rebuild the post-pandemic world.

"And for the global economy to recover, and for our domestic economies to bounce back, we need a global, co-ordinated plan," Trudeau said in a prepared text of his opening remarks.

"Our citizens need to have confidence in international institutions that leave no one behind and are capable of overcoming global challenges."

Trudeau is co-hosting the four-hour virtual conference, which was expected to include 50 heads of state and government, including Germany's Angela Merkel and France's Emmanuel Macron, along with representatives of the World Bank, the International Monetary Fund and the private sector.

Later Thursday, Trudeau will face a challenging meeting with the country's premiers as he broaches two topics that fall squarely within provincial jurisdiction: the operation of long-term care homes and paid sick leave for workers.

The issues are expected to be front and centre when he conducts his eleventh first ministers' conference call.

The prime minister has promised federal support in both areas but his offer has met with a mixed reaction from provincial and territorial leaders.

Quebec Premier Francois Legault appeared lukewarm about Trudeau's promise to ensure 10 days of paid sick leave for workers who fall ill with COVID-19 or are required to go into quarantine after exposure.

Legault said Wednesday there was "a very negative reaction from the corporate side," to the proposal.

"Well, obviously, there is a question there that isn't clear: Who will pay?" he said.

On long-term care homes, Legault came close to suggesting the feds should butt out, apart from sending the provinces more money for health care in general which they could then spend as they see fit.

At the outset of the pandemic, the federal government did increase those transfers by $500 million.

In contrast to Legault, Ontario Premier Doug Ford, has been effusive in his thanks for the offer of federal help.

"The prime minister offered his full support and I am grateful for the prime minister's commitment to working with us to solve this problem because we need their help if we're going to fix this broken system," he said Tuesday.

Ford too is calling for more federal funding but he's gone beyond that. As far as he's concerned, "everything is on the table," including integrating long-term care homes into the public health system, which is delivered by the provinces but under the national principles of the Canada Health Act.

Trudeau was careful Wednesday not to wade into the debate over national standards or bringing long-term care homes under the auspices of the Canada Health Act. He repeatedly stressed that the federal government will respect provincial jurisdiction as it embarks on discussion with the premiers.

This report by The Canadian Press was first published May 28, 2020.

With files from Michael MacDonald in Halifax and Joan Bryden in Ottawa