KITCHENER -- Waterloo Region's top doctor said local officials will no longer be tracking COVID-19 cases linked to social gatherings at the start of last month.

"It's not going to be possible for our team to continue to track additional cases," Dr. Hsiu-Li Wang said at the region's COVID-19 briefing on Thursday. "It becomes a community transmission."

Officials first identified the large cluster of cases on March 18, saying they were linked to private gatherings between March 4 and 7. As of March 18, there were 23 confirmed and one probable case associated with the cluster. Officials also said one of the initial cases had screened positive for a variant of concern.

The gatherings involved students at both the University of Waterloo and Wilfrid Laurier University.

Those cases are linked to an outbreak in all UW residence buildings, which now includes 27 cases.

On Tuesday, Dr. Wang said there were 85 confirmed cases and two probable cases associated with the large cluster from the gatherings.

"This large cluster has led to a significant community outbreak," she said.

Those cases included secondary transmission.

Dr. Wang said Thursday that it's now too difficult to continue tracking the cases linked back to those initial gatherings.

Feridun Hamdullahpur, president and vice-chancellor at UW, issued a stern message for students on Wednesday.

"For people who have acted recklessly and gathered repeatedly with people outside your household: we care about you and we are worried about your wellbeing. However, know that you’ve let us all down badly," the letter said in part. "Your behaviour risks your health and your education, and it needs to stop, now."

Waterloo Region reported 41 more COVID-19 cases on Thursday.

Premier Doug Ford announced the entire province would move into a shutdown as of 12:01 a.m. Saturday. Under the shutdown, non-essential businesses need to close and restaurants can only offer takeout and delivery. Essential stores can operate at 50 per cent capacity, while non-essential retail can open at 25 per cent capacity.