SUDBURY -- After a third student tested positive for COVID-19, the Rainbow District School Board has declared an outbreak at Lo-Ellen Park Secondary School in Greater Sudbury.

Public Health Sudbury & Districts told the board about the third case Sunday evening, the board said in a letter to parents Monday morning.

"A fifth class has been asked to self-isolate to and including Nov. 5," the board said. "In addition, the isolation period for a previous class has been extended to this date."

Under provincial guidelines, an outbreak is defined as two or more positive cases within 14 days that are linked where at least one person who tests positive likely was infected at school.

"However, Public Health has indicated that there is no evidence of widespread transmission at the school at this time," the board said. "For this reason, Lo-Ellen Park remains open for in-person learning."

The health unit will contact all parents and guardians considered a close contact of the students who have tested positive.

"Simply passing by an infected person in the hallway is not considered closed contact, and the risk of spreading the virus that way is extremely low," the board said.

"We remind parents/guardians to screen their children daily for symptoms of COVID-19 … Anyone who is sick must stay home."

The board has more information for parents and guardians on its website