EDMONTON -- An outbreak was declared at Edmonton's Ross Sheppard High School after a second case of COVID-19 was confirmed on Sept. 12.

According to a letter sent to parents and posted on the school's website on Sunday, the two cases are not related and neither was contracted at the school.

"AHS has advised us that 53 Grade 10 students and two staff members need to be tested and isolate at home for 14 days," the letter from Principal Rick Stanley reads. "If your child is required to isolate, you will have received a call from the school."

The school was cleaned before students returned Monday morning.

"The school will be contacting students and families today to arrange supports for learning, while they are required to isolate at home," the public school board told CTV News Edmonton. 

"The safety and wellness of our students, families and staff will always be our top priority, and we will continue to follow the safety strategies directed by the Government of Alberta. 

"We encourage families to self-monitor and contact Health Link at 811 should they require additional support from Alberta Health Services."

Ross Sheppard's first COVID-19 case was confirmed on Sept. 7.

Alberta classifies an outbreak at a school as two or more people attending the campus while infectious within a 14-day period, or when two or more people caught the virus in the school rather than community. 

In the case of Ross Sheppard, Alberta Health Services confirmed two school members had attended the high school while infectious. 

Chief Medical Officer of Health Dr. Deena Hinshaw said Monday afternoon the province had set the "extremely low" threshold of two cases for schools becuase it was important to trigger immediate precautions against transmission. 

She said families should consider the outbreak status a "sign that health officials are acting quickly and doing everything possible to support students' health and learning." 

Alberta's top doctor reiterated neither of the Ross Sheppard cases were contracted at the high school, and the significance of the public acting to reduce spread in their neighbourhoods. 

"While the total number of cases is not surprising, given the community transmission numbers we have, it's a reflection of the fact that we all need to do our part to minimize community transmission."

Edmonton's public school board is also monitoring cases at several other schools: 

  • One positive case at Westmount School. Just over 20 Grade 8 students and five staff members were sent home to isolate for two weeks and be tested. 
  • One positive case at Parkview School. Forty-six students in Grade 7 were sent home, along with six staff members. 
  • One positive case at Centre High. One staff member and 33 adult students were directed to isolate and be tested. 
  • One positive case at Vimy Ridge. Four staff members and 57 Grade 9 students were told to isolate. 

In the Edmonton Catholic school district, a total of nine schools have been affected and 62 people were isolating as of Monday: 

  • One person is self isolating at each Father Michael Troy, Louis St. Laurent and Archbishop MacDonald after a single positive case was identified at each of the schools in the first week of September. 
  • Two positive cases were found at Archbishop O'Leary on Sept. 9 and 10, but AHS said it is not considered an outbreak. Twenty-four people are self isolating becuase of the first case, and one more person is self isolating from the second. 
  • Six people were directed to self isolate after a single positive case at St. Edmund on Sept. 10. 
  • On Sept. 13, one case was identified at each Holy Trinity and St. Justin. At the first school, 25 people are isolating. One more person is self isolating at St. Justin. 
  • On Sept. 14, two cases were found at St. Catherin and St. Joseph. AHS did not direct any others to self isolate in connection. 

Deputy superintendent Tim Cusack said the two cases at Archbishop O'Leary was not classified as an outbreak becuase they were not connected or linked to the school. 

"These cases happened prior to school. There was no in-school spread. These were in the community."

According to government officials, 2,380 schools -- or 98 per cent of schools in Alberta -- remain open and operating without any cases of COVID-19. 

When there is one case identified at a school, it enters an "alert" status.