Oxford Public Health sent out the third and final suspension notice on Feb. 1.
All students are required to show immunization records or an exemption.
"If we don't have the information, that child will be suspended for a period of 20 school days or until we receive the information that we require," said Joanne Andrews, supervisor of health protection.
In Toronto, public health puts out three different notices over nine weeks: an initial warning letter, a second to parents who haven't responded, then a suspension notice.
Out of 350,000 Toronto students, about 6,000 get suspended each year.
"Parents think that their doctors let us know their child's immunization records and that's not the case," Dr. Vinita Dubey of Toronto Public Health said. "It's the parents' responsibility to let the public health departments know."
Parents in Toronto can submit their information online, or by phone or fax.