Education Minister Kirsty Williams has said that school children will have to be tested if they show any symptoms of the virus.
That will include any child with a cough, high temperature or loss of taste and smell.
“All children who are exhibiting a new continuous cough, temperature, loss of taste and smell, will be required to take a test,” she said.
“I appreciate that as we enter into the winter months other potential illnesses could well be confused but at this stage any child, or member of staff in school, are exhibiting any of these signs they will need to be tested.”
The education minister said she has “every confidence” in schools to ensure pupil safety as they return.
She said risk assessments have been carried out, and lessons learned from the return before the summer break.
Questioned on whether pupils would face sanctions for “malicious” coughing in classes, she said schools would have to rely on their behaviour policies.
“Exclusion should always be a last resort,” she said.
Education Minister Kirsty Williams also said that changes to the exam timetable in Wales next year could “go further” than what has been proposed in England.
She said that she intended for exams to go ahead but there could be changes to how the qualifications are taught, with examination board WJEC looking at making amendments to specifications.
It follows controversy after an algorithmic method of judging pupils’ grades was removed in favour of teacher assessments last month.
She said that Qualifications Wales are in discussion with UK regulators about a change to next summer’s exam timetable.
But she warned that any delay to next year’s exams might have a “knock-on effect” on matters such as progression and results day.