It is the first case of coronavirus at the Bolton Road school since the Autumn term began, but the academy says only a "small number of children" have been affected.
It has not said whether the individual who tested positive is a student or a member of staff, but did confirm that it was "within the school community".
The academy joins a growing list of schools in Lancashire where children have been sent home due to them, or members of staff, testing positive for the virus.
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Headteacher Peter Mayland said parents of the affected children have been informed by letter, with guidance on how they should remain indoors and avoid social contact for 14 days.
In an message to parents yesterday (September 29), he said: "We have been advised by Public Health England that there has been a confirmed case of COVID-19 within our school community.
"We know that you may find this concerning but we are continuing to monitor the situation and are working closely with Public Health England.
"This letter is to inform you of the current situation and provide advice on how to support your child.
"Please be reassured that for most people, coronavirus (COVID-19) will be a mild illness.
"The small number of children who have been in close contact with the individual who has tested positive for coronavirus (COVID-19) have received a letter informing them that they must stay at home for 14 days.
"The school remains open and your child should continue to attend as normal if they remain well.
"We will continue to follow our back to school safety steps in school."
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