The woman underwent 14 days of mandatory supervised quarantine in Victoria upon arriving back in Australia – during which she was tested twice for COVID-19 – before travelling to South Australia on a flight on Sunday.

Her two tests in Victoria came back negative, but upon taking a test in South Australia yesterday, she tested positive for the virus.

Deputy chief public health officer Dr Michael Cusack told reporters on Thursday the woman is not contagious is of “low risk” to the community.

He said she was not contagious on the flight and followed health advice by wearing personal protective equipment.

SA Pathology had to amplify its testing 40 times on the woman “just to be able to detect any particles of virus or any fragments of the virus”.

“Because it was so weakly positive we had to do further tests on a different platform to ascertain whether this was a true positive or not, and that then also returned a very weakly positive test,” Cusack said.

“This is someone who has had an infection – presumably in the previous two weeks or so – and now we’re seeing that they’ve still got a little bit of virus shedding, but they’re certainly not infectious or of risk to the public.”

Cusack said the woman and her family are currently in mandatory quarantine, with other family members receiving negative COVID-19 test results.

He said it was not “unusual” for a person to be tested negative for coronavirus before the virus is later detected.

“The scientists involved are working to see if there was something about the Victorian result that might have given us a clue here, but I think it’s more likely that because we have very, very low levels of virus, that… it would be easier for that low level to slip below the level of detection.

“If you keep repeating the test you will have instances where you get a negative result and if you test again you get a positive result.

“These tests do work.”

The new case is the first for South Australia in over two weeks and brings the state’s total to 444.

It comes as the State Government enforces mandatory testing for people who arrive in South Australia from Victoria within 24 hours and again on day 12 of quarantine.

The new measures will come into effect from midnight Saturday.

Those who flout the ruling face a $1000 on-the-spot fine.

“We’re sending a very strong message that it is absolutely mandatory to make sure that these tests are undertaken to keep our state safe,” Premier Steven Marshall said.

“As the risk has increased we have ratcheted up our response to that and this is another announcement where there will be a penalty applied to those people that aren’t doing the right thing.”

Meanwhile, Marshall criticised the sentence handed to four men who illegally travelled to South Australia from Victoria via a freight train as “disappointing” and “inadequate”.

The men allegedly boarded the train in Melbourne on Monday night and were arrested on Tuesday after it arrived at the Adelaide freight terminal.

In court on Wednesday, Jacob Todd and Nicholas Batty, both 29, Alexander Moore, 22 and Sam Gledhill, 26, admitted to breaking the rules when they snuck to Adelaide.

The men were placed on 12-month good behaviour bonds but had no convictions recorded.

The maximum penalty for breaching COVID-19 restrictions in SA is $20,000 per individual and $75,000 for a body corporate.

“I share the outrage of many South Australians who think this was completely and utterly inadequate,” Marshall said.

“The leniency showed, I think, was disappointing for our state.”

Marshall said the Government would look at options to increase penalties for people who illegally travel into South Australia, “but in this instance I just want to get these people out of South Australia”.

“I don’t want to lock them up in a prison that’s going to cost the taxpayer of South Australia $100,000 a year for every person that we’ve got in prison.”

The four men returned negative COVID-19 test results and will leave the state by the end of today.

– with AAP

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