As students prepare to head back to the classroom, teachers are also deciding whether or not they should go back to school.

Some have opted not to come, instead resigning or retiring early.

"It was a really difficult decision for some people," said Patrick Etmanski, president of the Ontario English Catholic Teachers Association Waterloo Unit.

Etmanski said about a dozen teachers have resigned or retired because of the COVID-19 pandemic.

"The people I have talked to said very clearly 'I'm not coming back, I'm not comfortable, I do not feel safe,'" he said.

He said some of the notices came just days before the start of class.

"I talked to a teacher yesterday who has decided to resign," Etmanski said. "Her main reason was she was returning to work today and still wasn't aware of what she was in for."

Etmanski said he anticipates more teachers will resign or retire as the school year continues, raising concerns about a shortage of supply staff.

"We may not have sufficient occasional teachers to cover the jobs that are going to come about," he said.

Ontario Secondary School Teachers' Federation Waterloo President Rob Gascho said there's still a lot of uncertainty.

"We'll see what level of difficulty or stress arises, whether we see any more people who decide that they just can't hang in there," Gascho said.

Brita Sherren, who is teaching Grade 4 this year, said she doesn't feel ready for the school year.

"We still have a lot of questions," she said.

Sherren added not everyone has the option to resign or retire. She also said teachers will need to get used to dealing with unknowns.

The first students in Waterloo Region went back to school on Tuesday. Both the public and Catholic school boards will continue to welcome students back in staggered schedules over the next couple of weeks.