Victorian officials and experts remain concerned about an aged care outbreak and the highly infectious Delta variant of COVID-19 as the planned end of Melbourne’s lockdown nears.
- Epidemiologist Nancy Baxter says she is “super concerned” about the source of the Delta strain being unknown
- The Burnet Institute’s Mike Toole says finding links for mystery cases becomes less important over time if there is no further spread
- Two aged care workers who have tested positive were not deemed close contacts and so were not in isolation
Health authorities remain no closer to understanding how a West Melbourne family of four contracted the Delta variant, which originated in India.
The strain is thought to be about 40 per cent more transmissible than the Alpha variant which originated in the UK, and more infectious still than the strains present during Victoria’s second wave.
“I’m still super concerned that we don’t know where that came from,” University of Melbourne epidemiologist Nancy Baxter told ABC Radio Melbourne.
There were 11 locally acquired cases announced by authorities on Monday, including two workers and a resident from the Arcare Maidstone aged care home, with no clear explanation for how the virus recently spread.
Four new cases, including three children, were linked to the West Melbourne family with the Delta variant.
The family tested positive after returning from a New South Wales holiday, and the cluster has now grown to at least 14.
Australian Medical Association (AMA) vice president Chris Moy said the variant had “popped up out of nowhere”.
“Unfortunately they do not know yet where it has come from and how far it has gone,” he told Afternoon Briefing.
Dr Moy said there was “a little bit of luck” in the fact the variant had been detected during a lockdown.
“But because they can’t find the head and tail of this, I think there is still significant concern about what decision needs to be made over the next few days,” Dr Moy said.
Restrictions are set to ease from Friday, but authorities say it is too early to tell whether it will be safe enough to do so.
Mystery cases ‘of less concern’ as time passes
Leading epidemiologist Mike Toole, from the Burnet Institute, said it may be that the index case in the Delta cluster is never identified.
Experts are working on the theory the virus escaped from hotel quarantine, but have cautioned genomic sequencing cannot be fully done with about 20 per cent of cases.
“As time goes by, that is of less concern than it was, say, a week ago,” Professor Toole said.
“Because there just hasn’t arisen from that original person, a chain of transmission that we didn’t know about before.
Professor Toole said it was “highly unlikely” there would be a “sudden surprise” of a group of unlinked cases emerging.
“I think overall, it’s pretty good,” he said.
The West Melbourne family is the first time the Delta strain has been detected in Victoria, and the first time this particular genome sequence has been found in Australia.
A NSW couple who tested positive to the Delta strain in early May after visiting a number of exposure sites, but did not transmit the virus to anyone.
“In the end, it didn’t really matter, because there was no spread,” Professor Toole said.
There are two other instances of mystery transmission in the current outbreak — how the virus spread from a Wollert man to what is now dubbed the City of Whittlesea outbreak, and how an aged care worker at Arcare Maidstone contracted the virus.
All of the infections linked to those two mystery cases have been confirmed to have the same Kappa strain of the virus the Wollert man caught in South Australian hotel quarantine.
Professor Baxter said with those mystery cases, contact tracers at least knew that the ultimate source of the infection was the Adelaide quarantine hotel.
“But here [with Delta], we have no idea how they got it,” she said.
She agreed that as more time passed, “the more relaxed I get about there not being broad community spread”.
“[But] there’s still a risk that that there is someone with a Delta variant out there that we don’t know about,” she said.
Concern in ‘most sensitive setting’ after new aged care cases
COVID-19 response commander Jeroen Weimar said the Arcare cases, and a new infection who had worked at a Queen Street construction site in the CBD, were his main focus.
There were just under 500 primary close contacts linked to the Queen Street site yesterday.
Mr Weimar said particular concern surrounded the new aged care cases as they were “clearly in our most sensitive setting”.
The two workers were not isolating at the time they tested positive.
“It is not clear at this time how the virus has been transmitted within the facility,” a federal Department of Health spokesperson said late on Monday. Infection control protocols are being reviewed, the spokesperson said.
During Victoria’s deadly second wave, more than 600 aged care residents died with COVID-19.
But Professor Toole said the fact residents had now been vaccinated, and that positive cases had been immediately transferred to hospital, meant there was more cause for optimism this time.
All but two residents vaccinated at Arcare home
The Department of Health confirmed that of 97 staff at the home, 77 had had one dose of the vaccine, while 47 were now fully vaccinated.
Two residents have opted not to get the jab.
The speed of the rollout to aged care residents and staff has prompted significant backlash against the federal government in recent weeks.
According to the department, 87 of the 110 staff members at the home have now received their first dose, and 13 are fully vaccinated.
Families of residents were briefed by the home on Monday afternoon about the latest in the outbreak.
Peta Soorkia, whose mother Mary Delilah Barkshire is a resident of the Magnolia wing, said she remained reassured by “the care and concern and the amount of effort that Arcare are putting in”.
The home is now testing daily, and more than 70 surge support staff have been brought in while staff deemed close contacts continue to quarantine.
Arcare and the Department of Health confirmed the staff all wore full PPE and had been fit-tested for their protective gear.
Ms Soorkia said she heard about the most recent cases from the news, rather than from the home, but had been told the protocols had now changed so family members would be the first to know of any new cases.
She said her mother had been keeping busy and the home had facilitated more video calls with family.
“So as long as we’re in contact with her, and she’s happy, and Arcare are doing what they need to do, which seems to be the case … as long as all that’s happening, then we’re not in the dark, then obviously, family must feel comfortable, I feel comfortable.”