Ontario is reporting 170 new cases of COVID-19 Thursday, bringing the provincial total to 858.

It is the largest single-day spike in cases by far.

Among the new cases are two Niagara residents; a woman in her 40s who recently travelled on a Caribbean cruise and a man in his 20s who travelled to Costa Rica, Spain and the United States. They are both in self-isolation.

A Halton woman in her 20s and a Hamilton woman in her 80s also tested positive for the virus. The province did not say where the senior contracted the virus but the Halton resident had recently travelled to the United States.

There is no information listed for a large amount of the new cases. At least 12 patients are being hospitalized, including two people in their 20s.

The total number of cases includes 13 people who have died and eight cases that have fully resolved.

There are currently 10,965 cases under investigation.