Local experts have added their voices to those questioning comments from South Australian authorities earlier this week suggesting that the outbreak was a “sneaky” new strain of the virus that was more contagious and likely to spread silently without causing symptoms.

Associate Professor Peter Speck, a virologist from the College of Science and Engineering at Flinders University, told InDaily he hadn’t seen “any evidence to suggest we’ve got any kind of super-strain here”.

He said he wouldn’t be surprised if it was “the same coronavirus strain as is circulating around the rest of the world”.

“I gather it came from someone who came from the UK… so I wouldn’t be surprised if it’s the same strain as in the UK,” he said.

“There was some suggestion of increased virulence… and this was the opposite of what (SA’s Chief Public Health Officer) Professor Nicola Spurrier was saying – she seemed to be saying it caused little or no symptoms in recipients… so if anything we are seeing something with less virulence.

“I think what’s happening is that the contact tracing and testing systems here are very, very good and they’ve been onto people who are infected very, very quickly and I think this is giving the impression of a virus that infects people very, very quickly.”

Speck said the incubation period reported worldwide was as short as two days.

“I suspect what we are seeing here is consistent with the extreme lower end of that range,” he said.

“But I think the action the authorities have taken, in view of what happened in Melbourne, you can totally understand why they’ve moved on this very decisively.”

Spurrier told media earlier this week the virus circulating in South Australia had a “very, very short incubation period”.

“That means when someone gets exposed, it’s taking 24 hours or even less for that person to become infectious to others,” she said.

“The other characteristic of the cases we’ve seen so far is they have had minimal symptoms and sometimes no symptoms but have been able to pass it on to other people.”

Premier Steven Marshall earlier this week described the virus as a “particularly sneaky… highly contagious strain”.

“The elements of this are quite frightening,” he said.

“It’s quite different than anything we’ve seen before.”

Professor Greg Dore, an infectious diseases physician and epidemiologist at the Kirby Institute, wrote on Twitter: “Rubbish.”

He told The Age and The Sydney Morning Herald it was more likely South Australia was simply misinterpreting its own test results.

“The virus has not changed at all. It’s just the detecting strategy,” he said.

Speck said: “I think viruses, in general, are very sneaky. I think this is a very sneaky virus there’s no question about it.

“And I think most people would agree it’s a frightening virus that’s caused over a million deaths worldwide.

“I think the Premier is trying to impress on South Australians the importance of the strong measures that were taken.”

But he said it was “ too early to say we have a super-strain here”.

“I haven’t seen any evidence to that effect,” he said.

“There’s a belief perhaps that what we’ve got here is a super quick strain and I can’t comment other than to say I suspect it’s simply an artefact of the excellent contact tracing and testing symptoms.”

Epidemiologist Professor Adrian Esterman, from the University of South Australia said: “It is doubtful it’s a new strain”.

“If this was a new strain, which has obviously come from the UK, then we would have heard about it,” he said.

“The very high probability is that it’s an existing strain acting in an unusual way.

“If testing is done incredibly frequently and testing is open to everyone… you will find different incubation periods.”

Asked about the Premier’s descriptions of the virus, Esterman said: “I think that was political poetry”.

“We can’t really describe (viruses) as being sneaky,” he said.

“They are bits of genetic material.”

“Yes this virus is incredibly contagious we know that. Is it very contagious? Yes. Is it far more contagious than we’ve seen elsewhere in the world? Probably not,” he said.

“The politicians make these statements not so much from a public health talk but more from a political talk.

“It is a bit of poetic licence.”

Today, Spurrier maintained her position.

“We still have the facts that this virus is highly transmissible and has a short incubation period,” she said.

“If we look at the original family… it was almost 100 per cent of the family members became positive.

“Previously when we had our first wave it was more like 20 or 30 per cent of family members would become positive.

“What we’re talking about is the genomics of the virus. This virus has come into SA from a returned Australian coming from the UK.”

She said it was the “first time” we’ve had this particular strain in South Australia.

“There’s nothing about the genomics in any way that makes it particularly special, it’s just that we can fingerprint it and track it back to where it came from,” she said.

“The real information we have got about this particular cluster is that it’s being passed on very rapidly and you’ve got that shorter incubation period.

“A genomically-similar strain has been described in New Zealand with similar characteristics.”

When asked today if he might have over-egged some of the rhetoric about the virus he’d used earlier in the week, the Premier was defiant.

“No, we know there were specific characteristics of the infection we had here in South Australia,” Marshall said.

“The specific characteristics of the genomics of this infection are that we know that there are low or no symptoms early on and that that transmission time is fairly short and this is quite different from what we’ve seen previously and that we’ve been managing previously.”