The largest outbreak was reported at Willowdale Welcome Centre, a shelter for refugees in the city's north end, said the CEO of Homes First Society, the organization that runs the facility.
"I'm worried about our clients, I'm worried about our management team, I'm worried about our staff, they're quite frightened," Patricia Mueller said.
She said 11 residents and 12 staff members have tested positive for COVID-19 at Willowdale. Seven more cases — three residents and four staffers — were also reported at two other shelters run by the company, which operates eight shelters in total across the city.
Mueller said two of the residents are in hospital for "precautionary reasons," but no one is in serious condition.
From there, those who test positive for COVID-19 are taken to a recovery centre if they do not need hospitalization.
The city said an interim recovery centre was set to open Tuesday.