Close contacts to five COVID-19 cases in Adelaide are preparing to leave hotel quarantine but health officials remain reluctant to shut the book on the concerning cluster.
No new cases have been linked to the outbreak associated with an adult learning centre which recently forced 94 close contacts into supervised isolation.
More than 1100 casual contacts were also asked to self-isolate at home.
On Friday, health officials said most had either reached the end of their quarantine or were close to it and no new infections had been found.
But Deputy Chief Public Health Officer Emily Kirkpatrick said it would take another incubation cycle before it became absolutely clear the danger had passed.
"I don't think we can say, at this stage, that we're out of the woods with that," she said.
"From a public health perspective, we are considering another fortnight to make sure there's no risk to the community."
SA reported one new COVID-19 case on Friday, with a man in his 30s who recently returned from overseas on a repatriation flight confirmed to have the disease.
He tested positive on day 12 of his two-week hotel isolation and will now spend another nine days in quarantine to ensure the virus is cleared from his system.
His case took the total number in SA since the start of the pandemic to 460 with only seven still considered active.
Testing rates also continued at high levels with more than 6800 across the state on Thursday.
That took the total number of swabs taken to more than 311,000 with about 13 per cent of the state's population taking at test at some stage.
The surge in test numbers in recent days has been prompted by the high rates of infection in Victoria with SA accordingly moving to impose new border measures.
From August 21, people living close to the border who come and go for school, work or shopping will no longer be allowed into South Australia unless they can comply with essential traveller requirements.
The change will likely prevent most trips for those who currently have permission to regularly leave and enter.
Health Minister Stephen Wade said the government made no apologies.
"The border that we have is basically like a fire break," he said.
"We want to stop the COVID-19 bushfire from Melbourne becoming a spot fire in regional Victoria and leading on to bushfires in South Australia.
"We're making sure if COVID does become present again in South Australia we're well placed to suppress it."
Australian Associated Press