Breakout Covid-19 cluster sparks national hunt for source

Mystery surrounds the origins of a Covid-19 cluster of seven cases linked to a West Melbourne family who spent six days in NSW.

Victorian Acting Premier James Merlino in Melbourne on Friday. Picture: David Crosling

Health authorities in multiple states are checking genomic ­sequencing data for all known Delta variant cases of coronavirus in Australia, as mystery surrounds the origins of a cluster of seven cases linked to a West Melbourne family who spent six days in NSW.

The revelation that the seven cases are unrelated to Melbourne’s other community-­acquired cases came amid confusion over the ­Andrews government’s handling of two false positive cases revealed late on Thursday, which contributed to Wednesday’s decision to extend Melbourne’s lockdown.

Business groups and the state opposition called for the lockdown to end as soon as possible, as Victoria recorded four new cases, all of which were in quarantine and close contacts of existing cases.

Of 67 community-acquired cases diagnosed in Victoria since a man in his 30s caught the virus in an Adelaide quarantine hotel and returned to the outer northern Melbourne suburb of Wollert on May 4, 54 are linked to the main Whittlesea cluster across Melbourne’s northern suburbs and an associated workplace in Port Melbourne, while five are associated with a cluster linked to the Arcare aged-care facility in Maidstone in Melbourne’s west.

The direct links between the Wollert man, the Whittlesea cluster and the Arcare outbreak have not been established, but genomic sequencing has shown all are cases of the Indian B. 1.617.1 Kappa variant of coronavirus which originate from the Wollert case.

On Friday, chief health officer Brett Sutton revealed genomic ­sequencing had found the West Melbourne cases were the more concerning B. 1.617.2 Delta Indian variant, meaning they are not linked to Melbourne’s other cases.

The West Melbourne cluster was first detected on Tuesday in a man who had driven with his family to Jervis Bay on the NSW south coast, via Gundagai and Goulburn, camping in the Booderee National Park from May 19 and visiting several local towns, before returning to Melbourne via the same route on May 24.

Between May 25 and May 31, the man, his female partner and their two children visited a range of sites in the Melbourne CBD and near their West Melbourne home, including North Melbourne Primary School.

Initially authorities believed the man, who developed symptoms on May 25, had likely only been infectious from May 23. But when his partner and children returned positive results on Wednesday, they extended the likely infectious period to at least May 19 — the first day of the family’s NSW holiday. On Friday, a Grade Five North Melbourne student who is a classmate of one of the family’s children tested positive, as did the child’s parents.

Professor Sutton said it was “absolutely” within the bounds of possibility that the family had contracted the virus in NSW, given the average incubation time for coronavirus is five or six days.

 

“Five or six days does put it ­potentially in NSW, Jervis Bay territory, or indeed earlier back in Victoria, so we have to be open to anything,” Professor Sutton said.

NSW Health Minister Brad Hazzard told 2GB that there was “no evidence whatsoever” that the family had picked up the virus in his state, given no match had been found on a national database of genomic sequences of all coronavirus cases in Australia.

“There is no evidence whatsoever that this family picked up the variant in NSW,” he said. “There’s no evidence, equally, that they picked it up in Victoria. There is simply no evidence at this time.”

Professor Sutton said health authorities nationwide would reassess genomic sequences of coronavirus cases. “That includes those who have come through formal quarantine, but also anyone else, maritime or airline, diplomatic or otherwise,” he said.

Asked whether the Delta strain revelation would have any bearing on Melbourne’s lockdown, Professor Sutton said: “We certainly have to identify what the origin is. It’ll make a huge difference if there are unknown chains of transmission that reveal themselves in Melbourne, versus none at all or in another jurisdiction.”

Melburnians are living under stay-at-home orders until at least midnight next Thursday.

Opposition Leader Michael O’Brien called on the government to ease restrictions in light of the two false positive cases, amid revelations the cases had received their negative results on Tuesday and Wednesday respectively. “When the government came out (on Wednesday) and announced the extended lockdown, it knew that (two of the) cases it was basing it on were at the very least questionable,” Mr O’Brien said.