Three year groups at a secondary school in Newport are currently self-isolating due to positive cases of coronavirus.
Years 7, 10 and 11 in St Joseph's Roman Catholic High School in Duffryn are the groups affected after positive cases were identified in each year in the past two weeks.
On Thursday the school said in a letter to parents that pupils in year 11 would have to self-isolate due to a positive case in the year.
"As your child was identified as a close contact on Tuesday, November 24, they should self-isolate up to and including Tuesday December 8. Your child should not return to school until Wednesday December 9," the letter from headteacher Jackie Jarrett said.
Earlier this week, the school notified parents in year 7 that a pupil in that year had tested positive for the virus, meaning all pupils in that year need to self-isolate until Friday, December 4.
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"Your child should not return to school until Monday, December 7," the letter said on Monday.
Students in year 10 are currently also self-isolating until Tuesday, December 1 after the school notified parents of a positive case in the year on Monday, November 16.
Pupils from year 8 returned to school on Tuesday after a two-week period of self-isolation following a case in that year.