The announcement followed Boston's first case of COVID-19 among the city's homeless population, the mayor said.

The new sites, which include 172 beds at Suffolk University's Nathan R. Miller Hall dormitory and 70 beds at the shuttered Kindred Hospital Boston in Brighton, are intended to ease the burden on existing shelters and slow the spread of the fast-moving virus.

Walsh said the city hopes that by adding resources for homeless people, it can ease the burden on health care facilities where they might otherwise wind up if they become sick on the streets or in overcrowded shelters.

The public health system is already being pushed to its limits by the crisis, with some skilled nursing facilities being converted into coronavirus treatment centers to relieve pressure on nearby hospitals.

"We're looking at how do we find and help as many populations as possible so we're not overwhelming our medical facilities and only the most serious cases go there," Walsh said. He added that there could be more sites coming into use soon.

The resources announced by Walsh are in addition to 55 new beds at other sites. The city is also working with the state to repurpose the Newton Pavilion at Boston Medical Center and will temporarily reopen it to meet the medical needs of homeless residents; that facility will provide 250 beds.

All told, Walsh announced about 550 new beds.

Suffolk University president Marisa Kelly said the university was relocating a handful of students who remained in the dormitory following a decision to move classes online in response to the virus.

She said the city reached out to the university administration to see if it could help with the crisis, and Suffolk readily agreed to donate the space. She said she anticipates that the building will be ready for use by students again in time for the fall semester, but given the uncertainty surrounding the COVID-19 outbreak, Kelly said she is prepared for anything.

The former hospital at 1515 Commonwealth Ave. is owned by the Davis Cos., which has proposed a 250-unit housing development there. But the building has been idle as the project goes through the permitting process.

Stephen Davis, managing director at the company, said the hospital remained in good enough shape that the company and city were able to get it ready for reuse within a few weeks. Davis said the company has some experience in medical development, but he did not expect such a use for this site.

"Truly, what we saw here was we have this asset. It's just sitting there idle at the moment, and we thought it would be a way for us to lend a hand," Davis said.

Walsh on Sunday thanked the businesses that are helping out with the response to the crisis. But he added that all residents of the city and region can do a lot to limit the toll of the virus by adhering to the social distancing protocols that are in place to slow the spread of the coronavirus.

Walsh said he was becoming exasperated by reports of people gathering in groups to socialize or play basketball and soccer in city parks.

He noted that even young, healthy people can get the disease ― or pass it to more vulnerable loved ones. It's not worth the risk, he said.

"It's hard for all of us who appreciate freedoms and being able to live our lives," he said. "I'm hoping that no other generation has to go through what we're going through right now."