KITCHENER -- A staff member who went to school while waiting for results from a COVID-19 test went against "clear health and safety protocols," the school board's chairperson said.

The Waterloo Regional District School Board reported a positive COVID-19 case in the staff member at Centennial Public School in Waterloo on Nov. 17, and said the staff member last worked that same day.

Over the weekend, health officials reported two cases in students at the school. The students were asked to self-isolate after the staff member went to work while they were infectious, and an outbreak was declared.

"We understand the feelings some of our school communities must be experiencing in being directed to self-isolate and we regret the stress that this has caused," Jayne Herring, board chair, said in a letter. "These are anxious times for so many."

Herring added that it was a serious situation that wouldn't be taken lightly.

She added that they're investigating the circumstances around the case. The Ministry of Labour visited the school last week.

"While these words cannot change what happened, please know that we are doing all we can to ensure that it does not happen again," Herring said. "Again, we regret that this has caused additional stress for our community during an already stressful time."