Ontario is reporting 441 new COVID-19 cases and three more deaths from the virus.
Health Minister Christine Elliott says 268 of the new infections are in people who are not fully vaccinated or whose vaccination status is unknown.
She says 173 of the new cases are in fully vaccinated people.
The province says 134 people are in intensive care with COVID-19 related critical illness, including 78 people on ventilators.
There were 15 patients from Saskatchewan in Ontario intensive care units as of Monday.
The province says 85 per cent of Ontario residents aged 12 and older have received two doses of a COVID-19 vaccine and 88 per cent have had one shot.