Kingsmead School in Hednesford sent a letter to parents on Monday confirming a pupil has tested positive.
The whole year group has been asked to self-isolate until September 25 and return to school on September 28.
Head of school Maria Mincher said: "We are writing to inform you that we have a child in Year 7 who has tested positive for Covid-19.
"We are grateful to the family concerned that due to their prompt action the child was not in school when symptomatic. However, we realise that this will create anxiety and stress for some families.
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"Please be assured that we have followed our risk assessment and Covid reporting procedures and are working closely with both Public Health England and the Local Health Team at Staffordshire County Council.
"Following the advice we have been given by the Health protection team we have asked the whole year group to self-isolate for 14 days from when the child who tested positive, first developed symptoms.
"Students are asked to self-isolate up to Friday 25th September which is a school training day. Students will return to school on Monday 28th September.
"This is a completely precautionary measure to ensure the safety of all concerned because this is the second case reported in this year group.
"Other students are not affected as a result of our carefully planned year group hubs, the compulsory use of face masks on corridors, recreation zones and regular deep cleaning throughout the day.
"Staff are not affected as they have kept the required distance from the students and maintained good hygiene in well ventilated rooms.
"The students who are self-isolating will be set work through show my homework our online platform.
"Their class teacher will be available for each lesson to check work to ensure that the students are supported in their blended learning.
"Work will be set by subject specialists and students will complete the work set each day.
"The students will receive a well-being phone call from a member of staff to support during their isolation and to ensure that safeguarding procedures are covered.
"At this point we will be able to provide extra instructions if your child is unsure of how to access work.
"If there are any issues with this, please contact us on this number 07395 902120 or 01543 227325 to speak to Mrs. Taylor, Assistant Progress Leader for Year 7.
"Only the identified students need to self-isolate. Household members such as siblings and parents of those students who are sent home do not need to self-isolate unless the student who is self-isolating subsequently develops symptoms.
"Self-isolation means remaining completely isolated within their home and not mixing with anyone else outside of their home for 14 days. If anyone in the family experiences any Covid19 symptoms, they must self-isolate and seek a Covid19 test as soon as possible. Please keep us informed of any change in circumstances on 07395 902120 or 01543 227325 or attendance on 01543 227324
"With the local and national picture changing frequently, I can assure you that the school is constantly reviewing its risk assessment, procedures and practice to keep our school community safe.
"The welfare of our students and staff is paramount and we will continue to deliver high quality learning experiences for everyone, even in these difficult times.
"I appreciate your support with remaining calm and measured in response to this situation."
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