Victoria has confirmed 11 more coronavirus cases, including two linked to aged care that were reported on Sunday.
State health authorities later confirmed all 11 were linked to the outbreaks that have spread across Melbourne in recent weeks, sparking its fourth pandemic lockdown.
“Eight are existing primary close contacts who were quarantining during their infectious period,” they said in a tweet.
Monday’s figures came from 24,265 tests in the previous 24 hours. There were 17,719 vaccine doses administered in the same period.
Victorian health authorities will provide a fuller update later on Monday.
Melbourne’s extended lockdown is due to end at midnight on Thursday, although there is yet to be confirmation that will go ahead.
On Sunday, deputy chief health officer Allen Cheng said the state was running “neck and neck” with the virus. However, he said an easing of restrictions was likely.
“Given 5 per cent of Victorians have been tested in the past seven days, if there was a big outbreak going on I would expect to have picked it up,” he said.
“That risk does fall over time but we are still concerned about that and that is where all our efforts are going.”
One of the cases linked to the Arcare Maidstone aged-care home in Melbourne’s inner-north-west is a 79-year-old resident who has had both doses of the Pfizer vaccine. They live close to two other residents, aged 99 and 89, who have previously tested positive.
The resident, who is asymptomatic, is in hospital.
The other case is a registered nurse who worked at the home on Saturday, is also asymptomatic and has received a first COVID-19 shot.
Melbourne has three coronavirus outbreaks with unknown sources: the Whittlesea cluster, which began with a Wollert man who left hotel quarantine in early May; the Arcare outbreak and the outbreak of the Delta variant of the virus linked to West Melbourne.
Professor Cheng said as time went on and the virus’s 14-day incubation cycle ran out, officials would become less concerned about finding the exact source of the outbreak.
“I think it’s fair to say that, with the passage of time, we get more comfortable with unknown source cases if they haven’t transmitted or there’s no hidden transmission going on after one to three weeks,” he said.
Only 2-3 per cent of Victorians have so far been fully vaccinated.
Professor Cheng said it was difficult to say what proportion would need to be vaccinated to avoid future lockdowns.
“There isn’t one single magic number,” he said.
“Once you get up to much higher coverage rates, then it makes a whole lot of things easier.
“We may not need the intensity of restrictions. We may be able to only do contact tracing without having to do other things quite to the same level, and that is the benefit of vaccination.”