There were also no further virus-related deaths.
The state is currently managing 33,290 active cases, a reduction of about 500 over the 24 hour reporting period.
There are 278 South Australians with COVID-19 in hospital. Twenty four of them are in intensive care and six are being ventilated.
Of the hospitalised, 162 people are fully vaccinated, 42 are either unvaccinated or partially so and 74 have an unknown status.
Some 90.2 per cent of South Australians aged 12 or over are double vaccinated while more than 463,497 booster shots have been issued, more than 11,000 of them in the past 24 hours.
Premier Steven Marshall said the latest case numbers were the state's lowest since late December.
"This is fantastic news and more proof that we are at, about, or maybe even slightly past, the peak in South Australia," he declared on Sunday.
"The statistics we've got today are very positive but we can't be complacent.
"My strong message to every single person in the state is to make sure that you and your family are all vaccinated."
Mr Marshall said the number of SA Health staff testing positive or being furloughed had "significantly decreased" to 596.
Despite this, the state branch of the Australian Nursing and Midwifery Federation claims new nursing graduates at Port Augusta Hospital are being left in charge of wards in a clear breach of rules.
CEO Elizabeth Dabars says new staff are feeling overwhelmed with minimal support after 34 resignations at the facility in the past six months.
"We warned back in October about the dangers of young graduates being thrown into the deep end,'' Professor Dabars said.
Of high concern is that a solo nurse was allegedly left to look after COVID positive patients overnight in full PPE without a break or back-up.
The COVID ward is isolated from line of sight to other workers, with doors closed and people warned to not enter.
The issue has been reported to SafeWork SA.
Mr Marshall said on Friday the latest preliminary modelling indicated there would be no significant jump in COVID-19 cases once school returned early next month.
Surveillance rapid antigen testing will be introduced for teachers and other staff in pre-schools and childcare centres.
The state's blanket work from home advice will also be revised on Thursday with workplaces asked to restrict attendance to 25 per cent of the usual capacity or about one person to every four square metres.
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