OTTAWA -- If Canadians want to avoid more pandemic-induced lockdowns, they need to do their part in keeping an expected second wave of COVID-19 infections under control by wearing masks, Prime Minister Justin Trudeau said Thursday.

As authorities prepare for a possible new surge of COVID-19 infections in the fall, key to controlling future outbreaks will be individual actions that citizens take, including wearing a mask when physical distancing is not possible, Trudeau said.

Pandemics often produce more than one surge in infections, he told reporters. And governments across the country need to be ready to rapidly test people, trace their contacts and isolate positive cases, he said.

But he added that individuals also need to do their part.

"We know there is more to do, and as we reopen, we know that citizens will continue to be extremely vigilant and careful about how they act because that is going to be a key part of keeping us safe moving forward," he said.

On Wednesday, Dr. Theresa Tam, the chief public health officer for Canada, recommended Canadians wear non-medical face masks in public when they aren't sure they will be able to physically distance.

Her comments were a turnaround from her advice seven weeks ago that people who are not sick should not be wearing a face mask at all. But as people leave their homes to shop in stores and enjoy the warm weather, mask-wearing can help slow the spread of the virus, she said.

Tam told reporters Thursday that "this is quite a difficult period" because people are getting fatigued from isolating at home, which induces people to forget the core public health directives.

"Right now is not the time to forget," she said.

Canada doesn't have a particularly high immunity rate from COVID-19, she said, because most of the population has not contracted the virus. That means "there will be susceptible people, and if they reignite a chain of transmission, you have to jump on that really fast," she said.

"This virus can accelerate really quickly."

Also Thursday, Trudeau said the federal government is sending $75 million to organizations that help Indigenous people living in urban areas and off reserves through the COVID-19 pandemic.

More than a million Indigenous people live in cities or off reserves, Trudeau said, and they deserve good services that are culturally appropriate.

This report by The Canadian Press was first published May 21, 2020.

-- By Giuseppe Valiante in Montreal