South Australians have been urged to complete any quarantine periods and follow COVID-19 restrictions to ensure no flare-up in a local cluster of virus cases.
SA reported two new infections on Thursday, 10 days after their first case was discovered.
Both were already in hotel quarantine when they became infectious, posing no threat to the wider community.
But Chief Public Health Officer Nicola Spurrier says the new cases show that people can still become ill and emphasised the need for everyone in directed home quarantine to complete the full 14 days.
“Even at this late stage, it is still possible for people to become positive,” she said.
“You can be highly infectious, even if you haven't had any symptoms yourself.”
The latest cases take the current outbreak to 21 since it first emerged on July 19.
One case involves a woman in her 80s, who is the wife of a man who also has the virus, and the second is a man in his 40s, whose two adult children previously tested positive.
Professor Spurrier said the growth in the number of cases in NSW also continued to pose a real risk to South Australia with a significant number of people seeking to return to the state.
She said all options were being considered to bring those people back.
Premier Steven Marshall said some exemptions had already been granted but officials would continue to take a careful approach.
“We've really got to manage this risk at the moment. My primary concern is the health of all South Australians,” the premier said.
“We'll manage these applications but we'll do it in a prudent way.”
At the same time, SA's transition committee has decided against any immediate change to border restrictions which prevent most people in NSW and Victoria coming to South Australia.
The state's so-called Modbury cluster of coronavirus cases began with an 81-year-old man who recently arrived in Australia from Argentina and was quarantined in Sydney before travelling to Adelaide, where he tested positive.
It prompted a week-long statewide lockdown which was lifted on Wednesday.