KITCHENER -- Schools in Wellington-Dufferin-Guelph have moved to virtual learning until at least April 18.

"If you had told me a week ago I was going to be closing the schools, I probably wold have thought 'No, I don't think so,'" Medical Officer of Health Dr. Nicola Mercer.

Dr. Mercer said there's been a spike in COVID-19 cases over the last five or six days in the health unit. The seven-day moving rate of school-aged children quadrupled in a two-week period from 25 to nearly 100.

Wellington-Dufferin-Guelph reported 297 new cases between April 1 and 6. There are 363 active cases in that region as of Tuesday. They've reported 5,546 cases of the disease to date, along with 5,077 recoveries and 106 deaths.

"All of these occurred much more rapidly than we've ever seen," Dr. Mercer said.

Dr. Nicola Mercer issued a Section 22 order on Tuesday, closing all in-person learning in the region.

Schools will open for in-person learning no earlier than April 19, with a possibility of extension.

"It really was a heartbreaking decision to have to close for an additional three days, adding on to the break," Dr. Mercer said. "But, I'm hoping that 12 days will be enough of a break to really interrupt transmission."

Gundi Barbour, the president of the Upper Grand EFTO, supports the decision.

"Given the extent of the variants we have and the anxiety teachers have because they cannot properly distance, many students are unmasked, there are a lot of health concerns, this was the best possible news that we could receive, frankly," Barbour said.

On Monday, officials in Peel Region announced schools would move to online learning on Tuesday and closed until at least April 18. Toronto schools will close on Wednesday.

Waterloo Region's Medical Officer of Health Dr. Hsiu-Li Wang said Monday she didn't plan to issue an order to close local schools at this time.

However, she said she's monitoring the situation closely and "will take additional actions as required."

Ontario NDP Leader Andrea Horwath is calling for the province to make schools safe for students and staff.

"(Medical officers of health) are forced into making these decisions, which then confuses people because it's not consistent," Horwath said.

Premier Doug Ford reiterated Tuesday that he believes schools are safe.

"Ninety-nine-point-eight-eight per cent of students do not have active cases, 99.32 per cent of students have never reported a case of COVID, 99.83 per cent of staff do not have an active case," Ford said.