But a leading epidemiologist says authorities should consider keeping schools open and sending home only the sick child and close contacts.

An Education Department spokesperson told InDaily there would be “no change” to the current practice of closing the whole school for at least a day to enable a deep clean, as soon as a student tests positive.

Authorities yesterday announced borders would open on November 23 to fully vaccinated people from interstate without having to quarantine except in some specific circumstances, allowing the virus to enter South Australia.

International visitors will also be allowed in but will have to quarantine for seven days.

That requirement will be removed once the state’s double vaccination rate hits 90 per cent which the Premier expects to happen before Christmas.

The Education Department is conducting a ventilation audit to see if any modifications are needed in schools to help reduce the spread of the virus.

Health Minister Stephen Wade has previously said “the evidence is not there for air purifiers” but the Education Department says nothing is being ruled in or out, until the audit is completed with results expected in early December.

The Education Department spokesperson said Victorian schools were using air purifiers but New South Wales schools were not – instead relying on ventilation such as opening windows and doors.

Deakin University Chair of Epidemiology Professor Catherine Bennett said instead of shutting down the whole school when a student tests positive, authorities should now consider keeping the school open and sending home only the sick child and close contacts.

“We’re learning more about transmission risk in schools which is lower amongst children than it is with adults,” she told InDaily.

Bennet said if teachers were vaccinated “that makes a difference and it allows schools to potentially stay open”.

“So moving away from a model that gives you that short notice, suddenly you’ve got a kid home for 24 hours, class is disrupted and parents have to manage it,” she said.

“With rapid antigen testing there are solutions that can actually keep it safe.

“Paediatricians have been saying ‘test to stay’ rather than kicking everyone out.

“As schools with the virus circulating manage outbreaks differently and it ends up being safe, then hopefully that will give states that aren’t living with the virus at the moment that level of reassurance that they can do this and keep schools open.

“That child might have to isolate while they’re unwell or while they’re infectious but if everyone else tests negative, you might then continue to test them on a daily basis or (for) the kids who are in that ring of greatest exposure – who sit close or hang out as friends – ask them to do home testing before they come in each day.

“I think that’s the way to look at it.

“It’s managing the risk in a very unobtrusive way.”

Bennett said authorities needed to “calm parents down”.

“The actual studies both in Victoria and in New South Wales looking at school cases show that the spread happens amongst teachers, not even really between teachers and students,” she said.

“That’s what parents need to know – it’s manageable, it’s not going to rip through schools, and the public health response might start to appear less thorough but in fact what it’s doing is just closing in to really focus risk management where it really does matter which is very close to that case.”

Another epidemiologist, Professor Adrian Esterman from the University of South Australia, said better ventilation would also need to be considered for workplaces once the state is living with the virus, and that a mix of working from home and the office should continue.

“In most office buildings the turnover of fresh air is about two to three times an hour – it needs to be more like five to six times an hour to keep the building safe,” Esterman told InDaily.

“Businesses need to talk to building engineers or their landlords about trying to improve airflow through the building, through their modern air conditioners, or install things like mobile air purifiers with heavy filters into meeting rooms.”

Esterman called on authorities to release more details about the opening up plan and better communicate their messages with South Australians.

“What they’ve given us is a sketch,” he said.

“We need to know more about ventilation, how we handle testing, what do we do if there’s an outbreak – will there be a localised lockdown?” he said.

“We will need to change what we are doing, we will never go back to pre-Covid.”

He said authorities should “pull out all stops” to lift vaccination levels in areas with poorer rates, such as the northern suburbs.

“We need high rates for the whole population, not just the wealthy suburbs,” he said.

Esterman said more vaccination hubs and mobile clinics were needed in those areas before the borders opened as well as better messaging about the options available.

Premier Steven Marshall yesterday said he was hopeful the state would reach a 90 per cent vaccination target by Christmas, allowing most local restrictions to lift and no quarantine requirements for fully vaccinated international arrivals.

Esterman agreed there was “a very high chance” of reaching that 90 per cent vaccination rate by Christmas.

Marshall today told reporters “further details are coming at the moment from the modellers associated with the Doherty Institute with specific information for South Australia that will really help us to frame those public health and social measures for later in the year”.

“We still need to put people who are infected into a quarantine situation and their close contacts because we don’t want this to progress very quickly,” he said.

Marshall said the government was “committed to sharing” modelling data which includes expected case numbers, hospitalisations and deaths, with final details expected “in the coming week”.

“There will be a number of people who become infected, we want to push that out into the future as much as possible and get that vaccination rate up even higher,” he said.

“But the numbers that we’re talking about are nowhere near the increase in capacity that we have put in place with our COVID-ready package.

“We’re talking about a peak that is still well into the future – on day one we’re not going to have large numbers here in South Australia.

“But all of that detail will be provided in the modelling that will be released.

“We are concerned about the number of cases, we’re more concerned about the number of people that will need to go to hospital and then the progression from hospital, into ICU and ultimately onto a ventilator.

“So we’re talking about very small numbers in those cohorts, we will see large numbers that become infected but what we know is that as we become more vaccinated here, we really reduce that transmission potential from where it was.”

Asked about the number of cases the modelling shows, Marshall said: “It depends what day, it depends on the vaccination rate on that day.”

“We’ve constructed a model, I think it’s very robust model, what we’ve then done is to say what is the situation in terms of our public health resources, both in terms of beds, in terms of programs for out-of-hospital care and in terms of resources, like nursing resources, and we put together our COVID Ready packages, a $123 million package, to make sure that we are 100 per cent COVID-ready for the inevitable cases,” he said.

“If you asked me what the model shows on the 30th of December, all that will be available, but it’s not a model that on day one, November 23, there is a prediction for the number of people that will be infected.

“This is why I understand that it’s reasonably complex and we’re still getting some final modelling as to what public health social measures need to remain in place.”

Asked whether the opening timeline was correct, Marshall said: “I’ve got some people telling me it’s too tough, some people telling me it’s too light.

“Some people don’t ever want to open the border, some people want to open the borders completely and immediately,” he said.

“What we can only do in South Australia is listen to that expert health advice.”