TORONTO -- Ontario's Chief Medical Officer of Health isn't ruling out the possibility that the province has now entered the second wave of COVID-19, as daily case counts continue to climb.

While Dr. David Williams wouldn't explicitly say whether the resurgence in cases constitutes a second wave, he acknowledged to CTV News Toronto that a second wave would feature "a significant and sustained increase in cases."

On Saturday, Ontario saw 407 new cases of COVID-19, leading to questions about whether the second wave of the pandemic has arrived.

"While we are unable to rule it out, it is easier to recognize a second wave once you are into it," Williams said in a statement to CTV News Toronto. 

Williams’s comments come after Ottawa's Chief Medical Officer of Health confirmed on Friday that the region is experiencing its second wave and expressed concern about the "speed of the increase" in cases. 

"We can’t sustain a rapid rise in cases," Dr. Vera Etches told reporters in Ottawa to Friday. 

Dr. Williams reluctance to define the current spike in cases could be attributed to the "range in scenarios" that public health officials have been relying on for their pandemic and flu season planning. 

"Scenario planning by the Public Health Agency of Canada and others include a range of scenarios, which includes a series of smaller waves or a major second wave," Dr. Williams said. 

Ryan Imgrund, a biostatistician with Southlake Regional Health Centre, believes Ontario has been in a second wave for at least a month and has projected a sharp surge without further intervention. 

"As it stands right now, we can expect to see 800 cases per day if we do nothing different by shortly after Thanksgiving," Imgrund said. "That's what the modelling is showing if we keep this growth rate up."

Premier Doug Ford was asked twice on Friday whether he believed Ontario was experiencing the second wave of the virus, but he premier sidestepped the question both times.