The Q3 Academy has shut for seven days after an outbreak of coronavirus meant not enough teachers were available to run the school.
Parents were told over the weekend the Wilderness Lane-based building would not reopen on Monday after multiple cases were reported.
Sandwell Council has said it is working with teachers, governors and public health officials to protect pupils.
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Mark Arnull, headteacher at Q3 Academy Great Barr, said the closure order was in the best interests of children and staff.
“We have taken the very difficult decision to close Q3 Academy Great Barr following consultation and advice from both Public Health and the Local Authority," he said.
“This is not a decision we have taken lightly and our goal is to minimise the risk to the health of children, staff and parents.
“We have done all we can to keep the school open but this closure is necessary due to a small number of our staff and students testing positive.
“This also means those who have been in contact with positive cases need to self-isolate. This is in-line with government rules and will help to prevent a further spread of Covid-19 within our school community.”
He added students could continue to learn through virtual lessons, adding: “Our staff have worked tirelessly to prepare and improve our online offer and will provide a first-class virtual learning programme for all our students.
“I would like to thank our students and their parents for their understanding and support during this difficult time.”
A spokesman for the council said: “Parents and carers can be assured that schools have infection control measures in place and will contact them should they need to take any action.
“When a case is confirmed that relates to an education setting, it is reported to Public Health England, which works with the setting and council’s public health team to ensure appropriate and proportionate measures are taken.
“Each school operates in a different way and depending on a number of factors (e.g. size, level of mixing between classes, who has tested positive, etc) the school, Public Health England and Sandwell Council will decide the most appropriate risk-based action.
“Our goal is to both minimise the risk to the health of children, staff and parents as well as limiting the impact to the education our school children receive.”
The school’s will reopen its doors on November 23 to all students except for Year 11 pupils who are preparing to take GCSE mock exams the following Monday.