Chief public health officer Professor Nicola Spurrier told reporters this morning that while modellers were certain that there would be a COVID-19 wave triggered by the emergence of the BA.4 and BA.5 Omicron sub-variants, they were unsure when the peak would occur or how many cases would be recorded at the height of it.

She said South Australia was “on track” to record between 5000 to 6000 cases within two weeks’ time in line with modelling released last week, but those figures were subject to change and the peak could hit earlier or indeed later than expected.

“They (the modellers) try to put all the most up to date pieces of evidence to try and estimate the model,” she said.

“Every couple of days as we get more data and they tweak the model to be a better indicator of what is actually happening here in our state.

“What they’ve (the modellers) said to me is the most certainty they have is around the fact that we will have a wave – they are less certain about the timing of it and the height.”

South Australia today reported 3300 new COVID-19 cases – up from the 3039 infections reported yesterday.

Overnight, 44 more people with COVID-19 were admitted to hospital, with the hospitalisation rate currently sitting at 284, including nine in intensive care and one on a ventilator.

A woman aged in her 80s died after testing positive for COVID-19.

Spurrier said daily case numbers were “definitely rising” in South Australia, with hospitalisations also set to increase in the coming weeks.

“If you have a look at our epi-curve, it’s definitely going up,” she said.

“If you have a look at the number of active cases that had got down to about 15-16,000 and now it’s considerably higher than that.

“Usually (hospitalisations) lag a couple of weeks behind our cases going up because it’s often the second week of somebody’s infection that they start to get into more significant trouble.”

Despite rising case numbers, Health Minister Chris Picton said the government was not considering reimposing restrictions or mask-wearing mandates inside public venues.

He said authorities were “continuing to monitor the situation”, but reimposing blanket rules would require the government to declare another state emergency.

Asked at what point the state government would consider declaring another emergency to deal with the COIVD-19 wave, Picton said the decision was “continually under review”.

“It would have to be determined on a case-by-case basis looking at all the various factors in place,” he said.

“It’s always been a factor that we have the ability if we needed to put that (emergency declaration) in place again.”

Chief public health officer Nicola Spurrier and Health Minister Chris Picton at a Mitcham pharmacy today. Photo: Tony Lewis/InDaily

It comes as the government this morning reduced the immunity period for South Australians who have had COVID-19 from 12 weeks down to 28 days.

The decision follows advice from the Australian Health Protection Principal Committee (AHPPC), which is the federal government’s peak decision-making body for disease control.

“BA.4 and BA.5 are associated with increased immune escape and we are likely to see rates of reinfection rise among those who have previously been infected with an earlier COVID-19 variant and those who are up to date with their vaccinations,” AHPPC said in a statement on Friday.

“Given reinfections may occur as early as 28 days after recovery from a previous COVID-19 infection, the AHPPC advises that the reinfection period be reduced from 12 weeks to 28 days.”

The decision means people who have recovered from the virus are now only exempt from being considered a close contact or a positive case for 28 days instead of 12 weeks.

“My expectation is that’s from today,” Spurrier said.

Picton said the AHPPC recommendation was “unfortunate” but reflected the reality of the new Omicron sub-variants.

“For 12 weeks people have had this get out of jail free card for COVID, unfortunately what we’re seeing with BA.4 and BA.5 has a lot more immune escape compared to previous strains,” he told ABC Radio Adelaide.

“If you’ve had BA.1 and BA.2 in previous waves that we’ve seen, that isn’t necessarily going to protect you from BA.4 and BA.5.”

Meanwhile South Australians aged 30 to 64 can from today come forward for a fourth dose – or second booster – of a COVID-19 vaccine.

The change in eligibility will see an extra 491,000 people eligible for a fourth shot in South Australia and 7.4 million across the country.

People over 50 are recommended to get the extra shot while those over 30 are eligible if they wish.

Spurrier and Picton both received their fourth vaccinations at a Mitcham pharmacy this morning.

Spurrier said she was “thrilled” to have the jab given the emergence of the BA.4 and BA.5 sub-variants.

“My last dose was the 6th of November last year so a really long time ago,” she said.

“I’ve been waiting and waiting and very pleased now that we’ve had this dose.”

Pharmacist Veronica Ferraro said there had been a surge in vaccination bookings since the eligibility change had been made.

“We’re getting quite booked out, so please jump online as soon as you can,” she said.

“We’re not immune from COVID here in the pharmacy either, so we’re dealing with staff shortages and everything, but we have plenty of stock, plenty of staff to give you your COVID vaccine when you’re ready.”