KITCHENER -- Some students at St. Mary’s High School in Kitchener were sent a letter Monday warning that they may have been exposed to a person who later tested positive for COVID-19.

Approximately 80 people received the letter.

It doesn’t indicate who the individual is – student, teacher or staff member – only that they are “a member of the St. Mary’s High School community.”

Their identity won’t be released for privacy reasons but they are one of nine confirmed cases of COVID-19 in Waterloo Region. As CTV News has previously reported, none of those confirmed cases includes a person under the age of 20.

Public Health says any possible exposure happened on March 9 and a letter was sent home with everyone who may have come in contact with that individual.

“We worked very closely with the school to identify all the people who could have potentially been exposed,” says Dr. Hsiu-Li Wang, the Associate Medical Officer of Health for the Region of Waterloo. “It doesn’t mean that they were actually exposed but we wanted to be very cautious so we went broader than absolutely necessary.”

She says the risk of transmission is low but they wanted to inform parents and members of the school as a precaution.

So why didn’t every student at St. Mary’s High School receive a letter?

Dr. Wang says it wasn’t necessary.

“It was a low risk situation and the potential risk was only for people in specific classroom settings.”

Public Health recommends that anyone who received a letter should self-monitor for symptoms for at least 14 days. If they develop a fever, cough or respiratory symptoms they are advised to self-isolate and follow-up with their healthcare provider and Public Health. Self-isolation can end once the individual is symptom-free for 24 hours.