CALGARY -- Alberta’s chief medical officer of health says for the first time, COVID-19 has been transmitted at school and a group advocating for teachers wants to know more about how it happened.

The infection was detected among two students at Waverley Elementary School in Edmonton. It’s believed one student contracted the virus in the community, then unwittingly passed it on to a schoolmate.

"This is not unexpected and is not a cause for alarm," said Dr. Deena Hinshaw Friday afternoon.

"Even with the cautious approach we have been taking, we expected that we would eventually see some examples of transmission in schools."

So far, 78 cases of COVID-19 have been found among staff and students at 57 of Alberta's 2,415 K-12 schools.

She says none of those patients became seriously ill or needed hospitalization.

That’s why some parents, such as Rick Norland, say they’ll keep their kids in the classroom.

"It does put me on alert," says the father of an 11-year-old boy.

"But I feel like we’ve to keep the day going, you know? Keep things rolling and just try to social distance as much as we can."

However, some groups are a little more concerned about the situation.

The Alberta Teachers Association says it wants the case of on-campus transmission to be investigated so officials can minimize the changes of it happening again.

"I think we need to do a thorough examination as to what the causes are of what happened here," said Jason Schilling of the ATA.

"(We need to) evaluate what’s been going on at the schools with the protocols. Do we need to reassess certain protocols to make sure the schools are safe for students or staff?"

In the meantime, staff and students at Bowness High School, the site of the first in-school COVID-19 cases in Alberta, will be returning to class on Monday. They've been self-isolating since the cases were first discovered by Alberta Health Services.

No further infections were reported among those staff members and students and all are expected to resume their school year.