Mr Marshall said a “circuit-breaker” was required to enable a contact-tracing “blitz”. Two new cases linked to the cluster were announced on Wednesday and there are an additional seven people who are suspected of being infectious.
Truck drivers entering Victoria from its western border will be requested to undergo testing from Thursday when the first checkpoint opens in Nhill, Victorian Health Minister Martin Foley announced.
But Mr Foley has conceded there was “absolutely nothing” stopping SA drivers from entering Victoria without health screening, despite those checks being mandatory for all air arrivals.
“Not at the moment because the risk criteria says that that’s not necessary,” Mr Foley told radio station 3AW on Wednesday morning, before Mr Marshall announced South Australia’s lockdown. “These things are a lot more manageable at airports.”
“We are very much relying on South Australia’s good will.”
Premier Daniel Andrews said a hard border closure was not out of the question, but was not deemed necessary at this point. South Australia’s restrictions ban non-essential travel.
“I don’t want to have to close the border but I don’t rule that out,” he told reporters in Wangaratta, where he announced the state government will offer Victorians $200 vouchers to stimulate tourism and the regional economy.
Mr Andrews warned if people ignored the government’s advice and travelled from SA into Victoria for non-essential reasons such as holidays authorities could tighten policing.
“If we see people who are travelling as if there hasn’t been an outbreak… well we’ll take the appropriate actions.”
The Premier said truck drivers who refused a test would be turned around, and anyone refusing a test arriving by air would be required to quarantine for 14 days. “There is no reason to refuse a test,” he said.
Victoria’s Police and Emergency Services Minister Lisa Neville revealed on Wednesday Victoria Police have been briefed on the prospect of establishing land border checks with South Australia.
“There’s been discussions with Victoria Police so that if we needed to close borders, they were ready for that,” she said.
“But at this stage, the priority is at airports and the checks that are going to happen with the truck drivers.”
Victoria’s Deputy Chief Health Officer Alan Cheng said all air travellers from South Australia who had been tested on Monday had received negative results and that there had been no travellers who had visited high-risk locations.
Two flights carrying 122 passengers arrived at Tullamarine airport from Adelaide on Monday. Authorities at the time said they tested 81 of those people. No flights arrived at Melbourne or Mildura on Tuesday. Two flights are expected on Wednesday afternoon.
There was minimal traffic coming into Victoria because South Australians would still be required to quarantine for two weeks when they arrived home again, Professor Cheng said.
“Most of the traffic across the border is border communities… [so] we put resources where there is the greatest risk.”
Victoria has categorised South Australian arrivals into three groups based on risk, Professor Cheng said.
Anyone who had visited “red zones” listed on the SA Health website, on the relevant dates, would be required to be tested and quarantine for 14 days upon arrival by air.
Those who had visited “amber zones” for the rest of metropolitan Adelaide would also need a test upon arrival, but only have to isolate until their results are returned, he said.
The rest of regional South Australia was not deemed as much of a risk and would go through basic health screening and interviewing.
Authorities are testing wastewater in Portland, Mildura, Hamilton, Horsham, Nhill, Halls Gap and Stawell.
Mr Foley said South Australians should only enter Victoria for the most critical reasons such as medical or funeral purposes.
“The exception to this, of course, is the border communities,” he told Nine’s Today program.
Current border “bubble” arrangements allow South Australian residents to travel to Victoria for any reason anywhere within a 70 kilometre cross-border corridor.
Announcing Victoria’s 19th consecutive “doughnut day” on Wednesday, the Department of Health and Human Services said the state processed more than 17,000 tests the previous day.
Victoria is remotely bolstering South Australia’s contact tracing capacity too, Professor Cheng said.
Mr Foley said it was “pretty much correct” to assume rules on outdoor mask-wearing would be eased as part of Victorian coronavirus restriction announcements on Sunday.
But he highlighted the important role of masks, pointing to the recent outbreak in Adelaide where masks have not been mandatory.
“Just think about what the situation had have been in Adelaide over the past week if they’d had [mandatory] masks,” he said.
Ahead of the the re-opening of the Victoria-NSW border next Monday, Premier Daniel Andrews clarified that Victorians would not be required to wear masks if visiting NSW.
“There was a bit of confusion the other day about where Victorian rules apply – they apply in Victoria of course, they don’t apply in other parts of the country,” he said.
“But if you come from the other side of the border into Victoria, the Victorian rules apply to you.”
The Adelaide cluster was only detected thanks to a diligent doctor who insisted a patient be tested, Australian Medical Association vice-president Chris Moy revealed on the Today Show.
There are three active cases in Victoria, two of which were still in hospital as of Tuesday. Professor Cheng said the patients were “pretty seriously unwell but stable”.
Public health officials have explained the long active period for the remaining three cases as being attributed to people who may be immunocompromised or still have symptoms beyond the 10 day isolation period, as people recover from COVID-19 at different rates.
With Josh Dye and Michael Fowler
Rachael Dexter is a breaking news reporter at The Age.