South Australia has avoided a “massive disaster” thanks to renewed COVID-19 restrictions with further evidence the Omicron outbreak is stabilising, Premier Steven Marshall says.

SA Health reported 2921 new infections on Tuesday, the lowest daily total for more than a week.

Hospital admissions rose to 211 and 22 people remained in intensive care with four on ventilation.

One more person died, a woman in her 50s, taking SA’s pandemic toll to 19.

Mr Marshall said new modelling on the recent surge suggested the peak was still to come but that local restrictions introduced in late December would significantly reduce the number of cases.

“We’ve been able to really avoid a massive disaster where the model was predicting tens and tens of thousands of cases on a daily basis,” he said.

“We now see that moderating very significantly because of behavioural changes in South Australia since we put those restrictions in place.”

The premier said officials were still determining exactly when the peak might hit — probably in the third or fourth week of January — and what the peak numbers would be.

“But what I can say is it is genuinely a fraction of where we were heading,” he said.

Mr Marshall said SA was also on track to switch on Thursday to allow close contacts of cases to have a rapid antigen test instead of a PCR test to reduce the demand on testing sites.

Under the new system, close contacts will be asked to register online to receive a QR code which will direct them to a testing site where they will be provided with two free RATs.

The change comes after testing centres had their hours cut on Tuesday because of soaring temperatures.

With the mercury set to hit 39C in Adelaide on Tuesday, a number of drive-through sites across the city were to shut down during the hottest part of the day.

Sites in regional centres were also affected.

“People who have made a booking for a COVID-19 test will receive a text message with further instructions,” SA Health said on its Facebook page.

“Bookings will be prioritised at the Victoria Park, Ridgehaven or Bedford Park testing sites.

“Other outdoor drive-through and walk-in testing sites may close at short notice due to hot weather.”

SA Health said people attending sites during the current conditions should remember to bring water and snacks, and those at walk-in sites should also remember sunscreen, a hat or umbrella, and a chair.

– AAP