Joyceville Institution in northeast Kingston, Ont., is dealing with a serious COVID-19 outbreak, Correctional Service Canada (CSC) confirmed to CBC News Thursday.

Currently, 80 inmates and four staff members at the medium-security prison have tested positive for the illness, CSC said in a statement.

CSC also confirmed five positive COVID-19 cases at Collins Bay Institution in Kingston and three more at Warkworth Institution, about 130 kilometres to the west. In a statement, a CSC spokesperson said infected inmates at those two institutions had recently been at Joyceville, and it appears that's where they were exposed.

All inmates recently transferred from Joyceville are being medically isolated and monitored for symptoms, CSC said. COVID-19 testing is being offered to all staff and inmates at those facilities.

On Wednesday, CSC suspended visits to its institutions in Ontario, and has said it's also implemented a series of infection prevention and control measures to help stop the spread of COVID-19.

"The health and safety of offenders, our employees, and the public remains our top priority throughout this public health pandemic. We continue to work with our public health partners, as well as unions and stakeholders to take any further steps needed to ensure everyone's safety," CSC said in a statement.

Justin Piché, an associate professor in the department of criminology at the University of Ottawa, said transferring inmates to other institutions shouldn't be happening right now.

He's been studying how correctional institutions have been responding to the pandemic and said Joyceville reporting an outbreak with 80 inmate cases shows too many people at the prison were interacting.

"[It] suggests that either prisoners, staff or both were having contact with people in units other than their own," he said.

Rob Finucan, regional president for the Union of Canadian Correctional Officers for Ontario, confirmed two of the staff members who tested positive were correctional officers.

He said an outbreak like this causes a lot of anxiety and undue stress in the work environment, especially so close to the holidays.

"A big concern for our members is that they get infected, then they bring it home to their families," Finucan said.

The union had been asking for in-person visits to institutions be stopped because visitors from hot-spot areas like Toronto and Peel were visiting.