Victorian authorities have dropped a bombshell revelation that the most infectious Covid-19 strain — called Delta — has arrived in Australia.
Victorian chief health officer Professor Brett Sutton told reporters that seven cases of the Delta strain had been identified as part of the West Melbourne cluster.
Four of the cases are from one family, made up of two adults and two children, who travelled to NSW’s Jervis Bay.
The other three cases are linked to another family made up of two parents and a child. Authorities are waiting on the test result from a fourth child in that family.
Melbourne University epidemiologist Professor Tony Blakely told news.com.au the emergence of the variant in Australia was very concerning.
“It means that we now have, not only the Kappa variant, but that Delta — the most infectious version of the coronavirus is here,” he said.
Another concerning factor is that genomic testing has so far been unable to identify any individuals in hotel quarantine with the exact same infection.
“There is a possibility that retesting will find a link to somebody in quarantine but if that doesn’t happen we will be in the same situation as the Wollert man again — we have to find out where the family picked up the infection from,” Prof Blakely said.
“The chase will be on to find the link.”
Authorities say it is possible the virus could have originated in NSW or regional Victoria and Prof Sutton said it was likely a grade five student at North Melbourne Primary School was the primary case.
He noted anecdotal reports indicated the Delta strain was more easily transmitted between children and there were also reports of more severe illness.
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Prof Blakely said if no link could be found, authorities would have to figure out how it just popped up.
“The only way would be through quarantine, and somewhere, somehow it got through quarantine without testing positive — which seems remote,” he said.
“There is a huge question mark over this and there will be a huge amount of detective work in the next 24 hours.
“Obviously this is an extremely concerning situation.”
Investigations by authorities will determine what measures are needed to control the spread of the highly infectious variant.
Prof Blakely said the Delta strain was about twice as infectious as the Wuhan wild-type that caused Melbourne’s second lockdown last year.
However, he said the good news was that while the virus is much more infectious, the mortality rate didn’t seem to be worse so it was not more deadly.
While there is not a lot of evidence about the effectiveness of vaccines in preventing the Delta strain, Prof Blakely said the limited data available indicated both the AstraZeneca and Pfizer vaccines worked okay against the strain.
Interestingly, NSW has not recorded any new cases since the Covid infections of the family who holidayed in Jervis Bay were discovered. Victoria’s case numbers also seem to be declining, with only four new cases identified today. There were no new cases associated with the Whittlesea, Port Melbourne or aged care clusters.
Prof Blakely said Victoria’s situation appeared to be looking up when it came to the Kappa infections.
“I think it’s going quite well — but it’s the Delta that’s thrown a spanner in the works,” he said.
He also noted that experts had been expecting Delta to pop up in Australia at some point.
“It just happens to be happening when Kappa has got out too,” he said.
Ironically he said Delta’s appearance while Victoria is already in lockdown could actually be a good thing as it would likely suppress the spread of the variant.
“If you’re ever going to have Delta pop up, having it pop up while we’re in lockdown is not a bad option,” he said.