“It’s a very surprising decision and if you look at Victoria it doesn’t seem to be necessary,” he said. “I’d like to see the health advice on which it was based.”
Victorian Premier Daniel Andrews said he wanted to avoid closing the border to SA, instead urging South Australians not to take advantage of Victoria’s open boundary and travel east without an essential reason.
“If we see people who are travelling as if there hasn’t been an outbreak … we’ll take the appropriate actions,” he said.
SA’s outbreak – sparked, like Victoria’s second wave, by a leakage from a quarantine hotel – grew by two cases to a total of 22 on Wednesday, with seven suspected cases awaiting test results and more than 4000 close contacts in self-isolation.
Mr Marshall said the six-day lockdown was needed to give the authorities breathing space for a “contact tracing blitz” and t protect the state’s most vulnerable.
“Time is of the essence. And we must act swiftly and decisively. We cannot wait to see how bad this becomes,” he said.
“We need a circuit-breaker to stay ahead of this … There is no second chance to stop a second wave. We are at a critical point, but we will get through this.”
The Adelaide outbreak is suspected to have started when a cleaner at a quarantine hotel contracted the virus then spread it to their large extended family. All cases in the outbreak are linked.
Chair of epidemiology at Deakin University Catherine Bennett said the six-day lockdown would give the SA Health Department enough time “that even if a case slips through the net … they won’t spark another grass fire, it will just whittle out, because they won’t have anyone to infect”.
Professor of biostatistics and epidemiology at the University of South Australia Adrian Esterman said six days would be enough time as long as restrictions were eased gradually.
SA Chief Public Health Officer Nicola Spurrier told reporters the strain of COVID-19 appeared to have a “very, very short incubation period”, with those infected showing symptoms within 24 hours of exposure.
But Mary-Louise McLaws, an epidemiologist with the University of NSW, cast doubt on the theory of a new, more infectious strain and said it was unlikely “the pathogenicity or the infectivity of the virus had changed”.
Victoria has so far resisted following the lead of Queensland, Tasmania, Western Australia and Northern Territory in introducing border closures or a 14-day quarantine on South Australians, instead sending health officials to Melbourne Airport to screen arrivals from Adelaide and mandating coronavirus tests for truck drivers crossing the border.
Despite the reluctance to enforce a hard border, Mr Andrews did not rule out the possibility on Wednesday and Police Minister Lisa Neville said Victoria Police had been briefed on the prospect of establishing land checkpoints with SA.
Mr Andrews warned truck drivers who refused a test would be turned around, and anyone arriving by air and refusing a test would be required to quarantine for 14 days.
As Victoria recorded its 19th consecutive day of zero new cases, Deputy Chief Health Officer Allen Cheng said the state was closely monitoring developments in SA.
“All cases in the outbreak in SA are currently within metropolitan Adelaide, so the risk to Victoria’s border communities is low,” he said.
SA’s slated reopening of its border to Victorians on December 1 will now likely hinge on the effectiveness of its six-day lockdown.
Professor Spurrier said the hard lockdown was critical to avoid a similar outbreak to Victoria’s second wave.
“If we leave this any longer … then we’re going to be in this for the long haul and we will be like the experience in Victoria, where we get increasing cases every single day, and we have to go into a significant lockdown for a very long period of time to snuff it out and and to get rid of every last bit of community transmission,” she said.
“Clearly, if it is reintroduced into a community, it takes off very quickly, and that is exactly what had happened in Victoria. I don’t want that to happen here in SA and I am going to do everything possible to make sure that doesn’t happen.”
Prime Minister Scott Morrison, who has repeatedly pushed for all Australia’s borders to be open at Christmas, thanked South Australians for their “patience and co-operation” and said the federal government would continue to support Mr Marshall’s government.
“These are precautionary and temporary measures with a clear end date,” the Prime Minister said.
The government will lift mutual obligation requirements for job-seekers in SA from Wednesday until November 29.
Australia’s acting Chief Medical Officer Paul Kelly said on Wednesday that all workers in the “major risk” quarantine facilities across the country would be tested weekly.
SA Police Commissioner Grant Steven said police were “on standby to attend if we see any civil disorder”.
“This is completely unacceptable [and there is] no need for panic buying,” he said.
The hard lockdown in SA comes ahead of Victoria’s next round of easing restrictions on Sunday, when hospitality venues will be able to host 200 people outdoors and public gatherings are expected grow to 50.
Michael is a state political reporter for The Age.
Rachael Dexter is a breaking news reporter at The Age.
Josh Dye is a news reporter with The Sydney Morning Herald.
Melissa Cunningham is The Age’s health reporter.