Melburnians are in the midst of their second week of lockdown and are anxiously awaiting its end on Thursday – but authorities need to see one thing before they give the go-ahead.
Today’s two unlinked cases are from the mutant Delta strain – a variant that is around 50 per cent more infectious than the typical covid.
Speaking to reporters today, chief medical officer Professor Brett Sutton said contact tracers did not know where the Delta outbreak came from but authorities could still have confidence to ease restrictions next week.
“If we only have those downstream cases and nothing else emerges, I am confident that those pillars of public health response, the contact tracing and the rings of control that we put in place, we will manage this,” he said.
“It is a challenge, the transmissibility, the secondary attack rate being 50 per cent greater than the Alpha variant, does mean that you can get a large number of people testing positive, you can get transmissions in other settings more readily. But we can still manage all of that.”
Testing Commander Jeroen Weimar said public health authorities were still working to bring the Delta outbreak under control but they were quickly “establishing a ring” around it.
Mr Weimar said the rapid response to the Delta outbreak left him confident “we will see that go to ground very quickly”.
“We recognise that by extending the lockdown in Melbourne, those are really costly days. It is a price the entire Melbourne community is paying these few days to make sure we are actually confident we are able to make a tough call in the coming days ahead,” he said.
Prof Sutton said even if the Delta cases were a mystery in the middle of next week, it would not necessarily stop discussions around ending lockdown.
“We just need to know every case that might be out there,” he said.
“I think that is manageable, and it does not impact on our decisions later in the week, but we have to be really clear that we need to find any cases that are out there.”
Victorian Health Minister Martin Foley said the discussion around ending lockdown wasn’t simple.
“As we approach next Thursday, the kind of facts we have been going through here are the evidence, what cases are out there, are there others linked or unlinked, have we got the support around them, have we got the evidence … as to knowing where they’ve come from,” he said.
Mr Foley said authorities were also looking for any upstream or downstream outbreaks.
“All these questions go into the mix and rest assured, the people of Victoria, we don’t want to keep the system in place for a moment longer than the public health advice says we need it in place,” he said.
“We will have more to say about that in coming days.”
Why are Delta strain cases so concerning?
B. 1.617.2, otherwise known as the Delta strain, is the same coronavirus strain that has decimated India.
It is also a major cause for concern in the United Kingdom.
US-based epidemiologist Eric Feighl-Ding explained the Delta variant was 50-70 per cent more transmissible and patients were 2.7x more likely to be hospitalised than other variants.
He said about 75 per cent of all cases in the UK were the Delta variant.
Professor Sharon Lewin from the Doherty Institute told ABC News this morning that there is existing concern over the “Kappa” variation – which has also emerged in Covid-stricken India.
Professor Lewin said both are about “double as infectious” than the UK variant “Alpha”.
“The Delta variant, this new cluster that was reported yesterday, is the dominant in the UK, and they’ve had a little bit of Kappa virus infection,” she said.
“From that country, the data is really good and the genomic sequencing is frequent. We do know that both of those variants are more infectious than the UK variant, which is now called the Alpha variant.
“The estimates are that they’re probably about double as infectious. So, for every person that one person would have infected – two people, previously – they’d perhaps infect double that now.”
She added that the severity of illness was “a lot less clear” at present, and currently based on anecdotal reports.
“You really need some very systematic data collection to prove disease severity, and I’m not sure we’ve seen that yet.”
“But the same measures still will work, meaning – test, trace, isolate, masks – all the usual things that we use to stop transmission will still work here,” Prof Lewin said.