TORONTO -- Toronto’s top doctor is urging residents to stay vigilant in adhering to public health measures as the city recorded the highest number of new COVID-19 cases since the beginning of the pandemic on Monday.

“Please, keep your guard up,” Dr. Eileen de Villa, Toronto’s medical officer of health, said as she reported the 643 new cases of the disease.

There are currently 249 people in Toronto in hospital with COVID-19 and 48 are in an intensive care unit, she said.

“I hope it does not take a high number like the one we have today to make that point resonate,” she said.

The new infections are nearly double what they were this time last week, when 331 cases were added. Since then, de Villa says the city’s case numbers have been fluctuating between the high 400s and the mid-500s.

Despite that, she says the high case numbers are “concerning in any measure.”

The news comes as Toronto enters its second week operating under the lockdown stage of the province’s COVID-19 framework.

Those restrictions, which are also in effect in Peel Region, prohibit most non-essential activities while restricting the use of gyms and onsite dining at restaurants and are set to extend for a minimum of 28 days.

De Villa underscored that while the measures are strict, time is required to determine their efficacy.

“We've seen the positive outcomes of distancing measures many times, in many places including right here in Toronto,” she said. “Time is needed to get a full picture as the new measures, take effect.”

In all likelihood, de Villa says, most of the infections reported in the last few days actually originated a week or two weeks ago, before those measures came into effect.

She said she hopes Torontonians “reflect briefly” on the case numbers reported today while renewing their commitment to keeping our “collective guard up.”

“By making smart choices about where we go, who we see and what we do and by renewing our commitment to doing all we can to limit the spread of the virus, we can prevent infections.”

It should be noted that the 643 cases reported by de Villa are slightly higher than the 622 cases reported by the province for the City of Toronto, though still a record. Local public health units report their case numbers at different times in the day and as a result case numbers reported by the province may differ from the case numbers reported by the city.