SA reported 4024 new cases on Monday, down from 4506 on Sunday.

"So this is really a stabilising of our numbers, in fact we've got to go back four days to get a day that was lower than what we had yesterday," Mr Marshall said.

"I think the restrictions that were put in place on 26th of December are now clearly showing we've been able to stop that massive escalation that other states around the country are currently experiencing."

Those restrictions include tougher density limits on most venues and a reduced cap on family gatherings.

The premier said he still expected the peak in virus numbers towards the end of January but a meeting with modellers on Tuesday would hopefully put a "finer point" on the likely date.

"People have said this is going to be short and sharp, I think they're right," he said.

"This is not going to be something that we're going to be lingering with for six months or 12 months.

"We are cautious here in South Australia but we're starting to see some real green shoots, some real improvement in our position over two weeks ago."

Despite the drop in cases, two more people have died with the virus, a man in his 90s and a woman in her 80s, taking SA's total deaths to 18.

The number of people in hospital has also grown to 188, with 21 in intensive care and four on ventilators.

Including those managing their infections at home, SA currently has 29,489 active cases.

Earlier on Monday, a parliamentary committee was told South Australia was considering using rapid antigen testing surveillance of teachers as part of a return to school strategy during the current surge in COVID-19 cases.

The state government is due to announce its plans for the new school year later this week, with health officials previously conceding there will likely be some disruptions.

Chief Public Health Officer Nicola Spurrier told the committee that SA Health was looking at RAT surveillance for teachers.

But she indicated that was unlikely to be extended to students at this stage, despite the fact most primary school children would not be fully vaccinated by the scheduled start date of January 31.

"We would need to have a look at the supply and we need to focus our resources on what is the best bang for our buck," Professor Spurrier said.

"The people who are at highest risk in our particular environment are people with symptoms and those who are close contacts."

The committee was also told that while SA had about 144,000 children aged between five and 11 who were still to be vaccinated, Health SA would receive only about 70,000 doses during January.

However, that number would be bolstered by doses provided to GPs and pharmacies, with the first doses allowed across both sectors from Monday.

South Australian Senator and Federal Finance Minister Simon Birmingham said taking into account the private providers, 54,700 doses had already arrived in SA, 40,000 more were scheduled to arrive this week and another 45,500 next week.

"That's more than 140,000 doses to cover every five to 11-year-old in SA whose parents want a first dose," he said.

Australian Associated Press