Ontario reported 321 new COVID-19 cases and two additional deaths on Tuesday, with officials now saying as many as 34 per cent of new cases involve partial or fully vaccinated individuals.

Tuesday’s count brought the rolling seven-day average of new cases to 306, up from 283 yesterday.

The last time the rolling average of new cases was at this level was June 24.

The province reported 325 new cases on Monday and a multi-month high of 423 on Sunday.

Provincial labs processed 16,479 test specimens, generating a positivity rate of at least 1.7 per cent.

There have now been 9,409 deaths confirmed in Ontario due to COVID-19, with 541,222 recovered cases.

There are a total of 2,494 known active cases of novel coronavirus infection across Ontario, the highest case burden seen since June 28.

Across Ontario, there were 96 new cases in Toronto, 30 in York and 31 in Peel. There were five new cases in Durham, 16 in Halton and 31 in Hamilton.

There were 109 patients in hospital ICUs due to COVID-19 on Tuesday, down from 113 yesterday and 106 one week ago.

Local public health units and hospital networks reported 115 people hospitalized due to COVID-19 in total across Ontario on Tuesday.

The province also released new data showing a growing percentage of Ontario’s new confirmed infections involve partially vaccinated and fully vaccinated people.

Of cases from the past two days, the province says 67 per cent were detected in unvaccinated people, 14 per cent were partially vaccinated (one dose or less than 14 days after receiving a second dose), and 20 per cent were in fully vaccinated individuals.

As of today, only 29 per cent of the province’s population remains unvaccinated.

However, the province's latest breakthrough infection data excludes any infection involving a person without a valid Ontario health card, regardless of their vaccination status.

Ontario had not disclosed breakthrough infection data for the last 16 days. Earlier data from Public Health Ontario suggested only 5 per cent of cases arose from vaccinated individuals.

They also broke down hospitalization data by vaccination status, but the numbers appeared to be incomplete.

It is believed the Delta coronavirus variant B.1.617.2 is responsible for the increased number of breakthrough cases, as it demonstrates an elevated ability to evade the neutralizing effect of vaccines.

Today’s breakdown reflects the experience of other heavily vaccinated jurisdictions such as Israel and Iceland, who are reporting significant numbers of breakthrough cases due to Delta.

The Ministry of Health says 48,278 more COVID-19 vaccine doses went into arms on Monday.

Of those, 10,416 were first doses and 37,862 were second doses.

The province now says 81 per cent of people age 12 and up have had at least one vaccine dose and 72 per cent have received two doses.

Dr. Kieran Moore, the chief medial officer of health in Ontario, said the rise in cases was always anticipated as we head into the fall.

"We’ve experienced a slow and steady rise in new cases of COVID-19 and Ontarians should expect to see a continued increase as we enter the fall. This is not a cause for panic. Our case rates will fluctuate over time and we can anticipate that they will continue to go up," he said Tuesday. 

"But it is our collective responsibility to avoid a sudden acceleration of cases by getting fully immunized... We need those who remain unvaccinated to step up."

The numbers used in this story are found in the Ontario Ministry of Health's COVID-19 Daily Epidemiologic Summary. The number of cases for any city or region may differ slightly from what is reported by the province, because local units report figures at different times.