A number of Bristol Grammar School pupils are self-isolating after a Year 13 student tested positive for coronavirus.
The 1,336-pupil all-through school on University Road, Clifton, informed parents of the Upper Sixth case on October 15.
Headmaster Jaideep Barot's letter reads: "I am writing to let you now that we have been made aware of a confirmed pupil case of Covid-19, within our Upper Sixth bubble.
"We have been in contact with the Department for Education (DfE) for advice on how to proceed and we are following all appropriate protocols.
"As a consequence, all close contacts of the affected individual are required to self-isolate for 14 days and they have been contacted separately."
A spokeswoman for the school said it was notified of the test outcome on October 15.
She said all pupils in close contact have been asked to self-isolate for 14 days, but did not confirm how many pupils or staff were affected.
Mr Barot added: “We have extensive safety measures in place to mitigate the risk of transmission.
"Despite pupils and staff following all that has been asked of them, the virus is such that simply sitting in a classroom, close to someone who subsequently tests positive, requires such action to prevent further spread.
“We hope that by following the advice from DfE and Public Health England, and asking those who have been in close proximity with the affected person to self-isolate, we will be able to limit any further spread within our community, as we head towards the end of this half of term.”
It comes hours after Bristol Live reported another confirmed case at St Katherine's secondary school in Abbots Leigh.
More than 50 schools in the Bristol area have confirmed cases since the start of the academic year in September - the full list can be found here.
You should book a Covid-19 test if your child has at least one of the following:
A high temperature - This means if they feel hot to touch on the chest or back. You do not need to measure their temperature.
A new continuous cough - This means coughing a lot for more than an hour, or three or more coughing episodes in 24 hours. If your child usually has a cough, it may be worse than usual).
A loss or change to their sense of smell or taste - They've noticed they cannot smell or taste anything, or things smell or taste different to normal.
If your child does not have symptoms of coronavirus but has other cold-like symptoms, such as a runny nose, they do not need to be tested.
They and members of your household do not need to self-isolate.
In those circumstances, your child can attend school if fit to do so.
