There are fears for thousands of students forced into isolation amid a growing Covid-19 cluster in South Australia.
The cluster in Adelaide grew to 20 on Tuesday.
The figures includes a student at Roma Mitchell Secondary College in Adelaide’s north who tested positive.
On Tuesday, the school was closed for a minimum of 24 hours.
“Families have been contacted and students will be released in a manner agreed with parents and carers,” the education department said.
“Students have been instructed to go home and stay there until further instructions.”
Roma Mitchell has more than 1100 students enrolled.
Meanwhile, Mawson Lakes School and its preschool have also been shut down until November 30.
The education department said a person who was possibly contagious visited the campus between November 11-13.
Anyone who was at the school or preschool is being considered as a close contact and is required to self-isolate for 14 days up to and including 27 November.
More than 890 students attend both Mawson Lakes School and preschool combined.
Premier Steven Marshall told Channel Nine’s Today Show it's believed the latest cluster started after the virus was spread from a surface.
Health Minister Stephen Wade told ABC News Breakfast, 17 of the infections were family members, two were security guards who worked at the medi-hotel where one of the family members work, while one is a close contact of the family.
He added early investigations indicated there was no breach at the medi-hotel where one of the family members, a 50-year-old woman, is believed to have contracted the virus.
The Parafield family cluster includes a one-year-old baby and three children.
More than 40 locations have been identified as being linked to the Parafield cluster as SA Health urged residents to monitor for symptoms.
From Tuesday all gyms, recreation centres and play cafes are closed for two weeks with community sports fixtures and training cancelled.
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