OTTAWA -- Three weeks into the new school year, Ottawa's school boards are facing a teacher shortage.

Ottawa's French Catholic school board says an average of 90 teachers a day have not been replaced this week due to a lack of supply teachers, while Ottawa's public school board warns schools may close without "sufficient" teacher coverage for students.

In statements to CTV News Ottawa, The Conseil des ecoles catholiques du Centre-Est (CECCE), the Ottawa Carleton District School Board and the Ottawa Catholic School Board confirm they are facing a shortage of teachers this year.  The boards are using teachers from the board office and unqualified individuals working in schools to help cover classes.

This week, the Ontario College of Teachers warned there is a shortage of certified teachers in the province due to the COVID-19 pandemic. In a letter sent to former and retired teachers, the college asks people to reinstate their memberships and return to work to help provide relief in the classroom.

The CECCE says it is facing a teacher shortage linked to the COVID-19 pandemic, adding the absenteeism rate of teachers has increased "considerably" due to self-isolation requirements as a preventive measure.

"In the past few days, an average of 90 teachers per day has not been replaced due to a lack of supply teachers. The CECCE has, on average, about 200 teachers on leave, per day, for various reasons," said the CECCE in a statement to CTV News Ottawa.

"For this reason, the CECCE appeals to the community to come and lend a hand to the school in its neighbourhood for student supervision tasks."

The Ottawa Catholic School Board says in the current COVID-19 climate, the board and others across the province are seeing an increase in the number of unfilled teaching jobs.  The board says it has approximately 750 qualified teachers who serve as Occasional Teachers, however; many of those individuals who are retired teachers who are only available for 50 days of service.

"Our principals problem-solve the challenge by assigning other school staff, such as resource teachers or guidance counsellors or vice-principals, to cover classes when needed," said the board in a statement to CTV News Ottawa.

The Ottawa Catholic School Board says schools will use the support of unqualified individuals to monitor classes.

Ottawa's public school board says it's seeing a "larger than normal shortage of teachers." In a statement to CTV News Ottawa, the Ottawa Carleton District School Board says, "this can be attributed in part to the pressures of having to distribute teachers across both in person and virtual schools, and in part to increased absences related to COVID-19."

The public school board says it continues to interview and add to the occasional teacher lists, use Designated Occasional Teachers and redeploy central teachers and non-classroom teachers within schools to cover classes.

"We are concerned that in cases of high absenteeism for example, where a large number of staff are self-isolating, it may not be possible to find sufficient replacements," said the OCDSB in a statement.

"Without sufficient teacher coverage for students there are health and safety concerns, particularly in elementary schools.  This could result in the closure of schools and/or the cancellation of virtual school classes."

Both the Ottawa Carleton District School Board and Ottawa Catholic School Board have positions posted on their websites for occasional teachers.

The Conseil des ecoles Catholiques Centre-Est has job positions for substitute and permanent teaching positions in Ottawa, Carleton Place, Kingston and Pembroke.