The province is now asking parents to keep their children home from school for 24 hours if they have either a runny nose or headache.
If a child has both of those symptoms they are asked to consult a health-care provider or have a COVID-19 test before returning to school or child care.
Previously, the government had asked that children with either single symptom stay home until they received a negative COVID-19 test or other medical diagnosis.
Ontario is also removing abdominal pain or conjunctivitis from its screening list.
Earlier this month, British Columbia removed 10 symptoms from their school screening sheet including runny nose.
Meanwhile, Ontario said it will give pay raises to personal support workers throughout the health-care system in a bid to recruit and retain them during the COVID-19 pandemic.
Premier Doug Ford said about 147,000 workers in long-term care, hospitals, and community care are eligible for the increase.
Personal support workers in long-term care and community care will be eligible for a $3 an hour pay increase, while personal support workers in hospitals will see a $2 an hour pay hike.
The temporary increase begins Thursday and will expire in March 2021, costing the government $461 million. Ford said he has not ruled out continuing the pay raise next year.
Advocates in the long-term care and home care sectors have said low pay has contributed to personal support worker shortages before and during the pandemic.
Ontario reported 538 new cases of COVID-19 Thursday and three new deaths from the illness.
Health Minister Christine Elliott said 229 cases were reported in Toronto, 101 cases in Peel Region, 66 in Ottawa, and 43 in York Region. She said 60 percent of the new cases were among people under the age of 40.
In total, 162 people are hospitalized in Ontario due to COVID-19, including 36 in intensive care.
The province also reported 65 new COVID-19 cases related to schools, including at least 29 among students. Those bring the number of schools with a reported case to 307 out of Ontario’s 4,828 publicly funded schools.