Correctional Services Canada is confirming another two cases of COVID-19 at Kitchener's womens prison.
The Grand Valley Institution for Women is now up to six positive cases.
A correctional officer also tested positive for the virus.
They say 31 inmates have been tested, with 24 coming back negative and one test is pending.
A lockdown is in place for about 40 inmates, all of them being contained to one unit.
Correctional staff are said to be restricting movement to help control the spread of the virus.