Ontario, Canada's most populous province, is expected to see intensive care capacity reach unsustainable levels in January without an "immediate circuit breaker" to stem the spread of Omicron variant, according to Ontario's Science Advisory Table on Thursday.

The Omicron variant is set to become the dominant strain in the province this week and without some type of circuit breaker, COVID-19 cases could exceed 10,000 per day before Christmas, according to the modeling issued by the Science Advisory Table.

"Although vaccines are less effective against Omicron infection, boosters can substantially increase protection," the modeling says. "Even two doses likely provide strong protection against severe illness. The risk of severe illness is dramatically higher in the unvaccinated."

Ontario, with a population of 14 million, reported 2,421 new COVID-19 cases on Thursday for the first time in seven months and as well as nine deaths related to the disease.

Out of the 2,421 cases, 758 are unvaccinated or partially vaccinated and 1,530 are in people who are fully vaccinated. Some 133 cases are in individuals with unknown vaccination status, according to the Ontario government.

Of the new cases reported on Thursday, 378 are in kids under the age of 12 and 241 cases are in youth between the ages of 12 and 19.

The number of COVID-19 cases reported daily in Ontario has been on a steady rise over the past few days, with 1,429 infections reported Tuesday and 1,808 infections on Wednesday.

The province's rolling seven-day average of COVID-19 cases now stands at about 1,674, up from 1,055 the previous week and its positivity rate soars to 7 percent.

The province confirmed 335 new school-related COVID-19 cases, including 278 infections in kids and 47 in staff members. Sixty schools in Ontario are now closed due to COVID-19.

There are 938 infections in people between the ages of 20 and 39 and 638 infections in individuals between the ages of 40 and 59. Some 222 cases are in people over the age of 60.

A little more than 90 percent of Ontarians aged 12 and up have received at least one dose of a COVID-19 vaccine while almost 88 percent have received both doses.

At a press conference in Ottawa on Wednesday, Canadian Health Minister Jean-Yves Duclos urged Canadians with plans to travel abroad to cancel their trips as the Omicron variant spreads worldwide.

"To those who were planning to travel, I say very clearly now is not the time to travel. The rapid spread of the Omicron variant on a global scale makes us fear the worst," Duclos said.

The rate of spread is huge, he said, and Canadians may find themselves stranded if countries impose lockdown measures or curb flights in and out.

"The situation abroad is already dire in many places and it's going to get worse very quickly, so we're afraid for what could happen to them if they leave Canada," Duclos said.

Wednesday evening, Canadian Prime Minister Justin Trudeau said he knew Canadians were looking forward to getting away, not having to think about COVID-19 but emphasized the importance of safety and caution in dealing with the Omicron variant and advised against non-essential travel.