Ontario is reporting close to 4,400 new COVID-19 cases today, the highest single-day total since the end of April.

Provincial health officials logged 4,383 new infections today, up from 3,453 on Tuesday and 1,808 one week ago. Today's total is the highest daily case count reported since April 23. 

The seven-day rolling average of new infections now stands at 3,520, more than double last Wednesday's average of 1,514.

Of the news cases confirmed today, 176 involve those who are partially vaccinated, 222 involve people with an unknown vaccination status, 746 involve those who are unvaccinated, and 3,243 involve people who are considered fully vaccinated with two doses of an approved COVID-19 vaccine.

The province says 10 more virus-related deaths were added to Ontario's COVID-19 death toll over the past 24 hours.

Case counts have surged over the past week as the highly contagious Omicron variant circulates widely in the province. The province's Science Advisory Table says the variant now represents about 91 per cent of all new cases and has a doubling time of 2.9 days.

With 55,381 tests processed over the past 24 hours, officials are reporting a provincewide positivity rate of 10.7 per cent, up from 6.6 per cent seven days ago. This is the highest positivity rate reported in Ontario since April 26.

Ontario's known, active COVID-19 caseload now stands at 28,288, up from 12,666 seven days ago.

The public health units with the highest number of new cases today include Toronto (1,284), York Region (479), Ottawa (363), Peel Region (335), Durham Region (238), and Halton Region (223).

Virus-related hospital admissions have risen to 420 today, up from 357 last Wednesday. Intensive care unit (ICU) admissions have also begun to rise, with 168 COVID-19 patients receiving treatment in the ICU, up from 154 one week ago.

There are 132 ICU patients who are not fully vaccinated or have an unknown vaccination status and 36 who are fully immunized.

About 88 per cent of people aged 12 and up in the province have received at least two doses of a COVID-19 vaccine.

Last week, the province announced that everyone 18 and older who received their second dose at least three months ago would be eligible for a booster shot to help provide better protection against Omicron.

But demand has far exceeded available appointments and many people have been unable to book a shot within the next month.

The province is encouraging Ontarians who still need a booster dose to try to get a shot at hospital clinics, pop-up sites, and through pharmacies if they are unable to find a timely appointment through the provincial booking system.

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.