Extra infection control measures have been implemented and testing of residents and staff has begun at a number of Adelaide nursing homes after two health workers tested positive for COVID-19.
SA Health says the workers visited and delivered care to residents at a number of sites before their infections were detected.
"Affected sites are being contacted by SA Health and supported to implement additional infection control measures, while testing of residents and staff is being undertaken," it said in a statement.
"SA Health is working closely with the Commonwealth Department of Health and the Aged Care Quality and Safety Commission to enact protocols to protect aged care residents and staff."
The development came as 12 new coronavirus cases were reported on Tuesday, including six with the source still under investigation.
The new infections take the total number of active cases in SA to 70 with more than 650 close contacts in quarantine.
Of the active infections, 28 are being managed in home isolation and 40 are in quarantine hotels.
The remaining two, a man in his 30s and a man in his 60s, are in hospital in a stable condition.
Despite the rising number of cases, South Australians will soon know what local restrictions will be eased when vaccine rates reach 90 per cent but the changes are now unlikely before Christmas.
The state's transition committee is expected to finalise its timeline by the end of the week.
SA is forecast to hit its 90 per cent target for those aged 12 and over by the end of the year, but probably not before December 25.
"We are working, as a collective, to come up with the optimum date to provide some clarity for people in South Australia on when things will be changing, based on the modelling in relation to when we are likely to hit 90 per cent," Police Commissioner Grant Stevens said.
"I was hopeful that it was going to be before but the indicators are at this stage that it will be after Christmas but before the end of the year."
Based on the latest state government figures 91.2 per cent of South Australians 12 and over had had at least one vaccine dose and 84.5 per cent both.
Among the changes to restrictions will be an easing of density rules and attendance caps.
