South Australia has recorded six COVID-related deaths and 3,023 new cases.
The deaths include a man in his 30s, two women and a man in their 80s, a man in his 90s and a woman over 100.
There are 298 people in hospital including 33 in intensive care and seven on ventilators.
SA Premier Steven Marshall said the fact that 6,906 people had recovered from COVID-19 in the past 24 hours, compared with the 3,023 new infections, was a further indication that the state was "at or about the peak".
"These numbers do bob around a bit but it is now significantly under our seven day average in South Australia," he said.
Of today's new cases, 2,253 came from PCR tests and 770 were recorded from rapid antigen tests.
The state now has 31,582 active cases.
Mr Marshall said the number of SA Health staff in isolation had decreased significantly to 416 COVID-positive staff with 614 in total furloughed.
South Australians have been encouraged to work from home for the past month, but the government will be "slowly encouraging people to return to work" from January 27.
Workers will be encouraged to wear masks, socially distance themselves from others, and eat meals outdoors where possible.
Chief Public Health Officer Professor Nicola Spurrier said the state was "at a fairly critical stage".
"It doesn't take much to increase transmission in our community so we need to look at things very carefully, very closely," she said.
Professor Spurrier said the public service would be allowing one in four, or 25 per cent of the workforce, to return to the office.
"There's still a lot of cases in our community and transmission can occur in office settings," she said.
New rules for positive cases in classrooms
The government also announced more details on its return to schools plan today.
Mr Marshall said new modelling shows "no noticeable jump whatsoever" in case numbers was expected when schools return under the hybrid model of mixed face-to-face and remote learning for the first couple of weeks of term.
"There will be some additional cases, but it's not a noticeable jump," he said.
Under the education plan, early learning and childcare educators will be provided rapid antigen tests to be used three times per week — but regular screening will not be done in schools.
Professor Spurrier said rapid antigen tests would be used in early childhood settings as the "best bang for our buck" because children were too young to be vaccinated or wear masks, and staff were in close contact with children.
"We don't have other risk mitigation we can put in those settings," she said.
A new definition of "classroom contact" has been established for positive cases within schools.
If a student tests positive, teachers will be given seven rapid antigen tests and will be required to return a negative test every morning.
As long as they have a negative test and no symptoms, they can continue coming to work.
Classmates of a positive case, or students of a positive teacher, will be asked to monitor for symptoms, but will be able to continue attending school.
School staff who have more than 15 minutes of face-to-face contact with other staff without masks will be deemed close contacts and will need to isolate for seven days.
There are separate guidelines for school services officers (SSOs), who often work closely with individual students.
Rapid antigen tests will be provided for free to schools and early education settings in a funding model split equally by the state and federal governments.
Professor Spurrier said classrooms reopening would inevitably see an increase in cases in children.
"We are expecting and it will be self-evident that there will likely be an uptick in infections in children or cases in children, but overall when you look at the whole population we are not expecting to get a second wave," she said.
