In the two weeks since classes resumed across the province, at least 1,000 students and staff in schools across Edmonton have been ordered into isolation after potential exposure to COVID-19.

The virus has disrupted K-12 education in Alberta, emptying classrooms and sending children home to quarantine while learning online, monitoring for symptoms and getting tested.

On Friday, as Alberta's top doctor confirmed the first likely-case of in-school transmission, the caseload continued to increase, with schools across the province reporting new cases.

To date, there have been 78 confirmed cases in 57 of Alberta's 2,415 schools.

In each case, when someone tests positive, the typical approach is to require entire classrooms to stay home for 14 days.

As of Friday, outbreaks had been declared at 13 Alberta schools. Outbreaks are declared when a school has two or more cases of COVID-19.

And while the province is carefully tracking potential outbreaks, and the number of people falling ill, the total number of students and educators being sent into isolation due to potential exposure is not as clear.

The total number of students and school staff in isolation across Alberta is not being centrally tracked by Alberta Health or Alberta Health Services.

In an email to CBC News, Alberta Health said it is "exploring ways" to provide these numbers to the public.

Edmonton's Catholic and public school districts began providing school-by-school data this week and an analysis by CBC News points to an increasing caseload in city schools.

Potential exposures multiplying

The first cases in Edmonton classrooms were confirmed Sept. 4 at École Sainte-Jeanne-d'Arc and Louis St. Laurent Catholic School. Since then, the potential exposures have multiplied.

As of Friday morning, at least 1,009 students and staff across both districts were under quarantine orders and at least 33 city schools were contending with confirmed cases.

In the Edmonton Public Schools district, 831 students and 67 staff members were in self isolation as of Friday. Fourteen schools had been affected by potential exposures.

Ross Sheppard High School, which identified its first case after only one day of classes, has among the highest potential exposure groups in the city with more than 200 students and staff now forced into the 14-day mandated quarantine period.

The first case at Ross Sheppard, confirmed on Sept. 8, sent nearly 100 students into isolation. Three classes of Grade 10 students and their teachers — close to 100 people — were told to quarantine after someone in the group tested positive.

A COVID-19 outbreak was declared at the school on Sept. 13 and there have now been three confirmed cases within the school population.

Centre High has the second largest isolation rate in Edmonton with more than 160 adult students asked to isolate after three different potential exposures from infected individuals.

Edmonton's Catholic schools have fared relatively better. As of Friday afternoon, a total of 111 students and staff had been ordered into isolation since the beginning of the school year with 18 schools affected.

Across Alberta, about 742,000 students are enrolled at more than 2,400 schools. As of October 2019, the Edmonton Catholic School Board reported enrolment at 44,300 across 96 schools. Edmonton Public Schools has over 100,000 enrolled students this year at more than 200 schools.

The numbers provided by school officials don't account for students sent home for testing after exhibiting symptoms such as cough, fever or runny nose. They are not tracked because they have not been linked to a confirmed COVID-19 case.

While the virus has been circulating among student populations for weeks, the first in-school transmission was confirmed on Friday.

In-school transmission 'not unexpected'

The second case at Edmonton's Waverley School was likely transmitted from another individual at the school who has tested positive, Dr. Deena Hinshaw, Alberta's chief medical officer of health, said at Friday's news conference.

Transmission within a school "was not unexpected and is not a cause for alarm," Hinshaw said.

"However, I know many are anxious about school safety and I felt it was important to share this information with you and to talk about what it means."

As the school year progresses and health officials learn more about how the novel coronavirus spreads, guidelines for self-isolation may be loosened or otherwise changed, Hinshaw said earlier in the week.

"I recognize that this is very inconvenient for families, and I regret the impact that this is having on those students and their families," she said.

"The reason for this approach is to gather information about who is most at risk of getting COVID-19 from a school exposure. This will enable us to target exclusions in the future to only those who are most at risk."