Dunrossness Primary School imposed a 48-hour closure on Thursday after an outbreak of the winter vomiting bug, Norovirus.
School officials say the decision to remain shut until Monday follows unfortunate incidents in which both pupils and staff were struck ill by the virus.
Director of the council’s children’s services, Helen Budge, said that the decision was made to keep the bug contained.
Moves will also be made to clean the school and the time off will also give those affected time to recover.
“The decision was taken, and I absolutely think it is the right decision,” she said.
“It got to the stage that the number of staff being off meant it was going to make it very difficult to cover everything.”