A Melbourne aged care resident has tested positive to COVID-19 a day after it was revealed a worker at the same facility had contracted the virus.
Victorian health authorities announced 11 new community cases on Monday, taking the total number of infections linked to the outbreak to 51 and primary close contacts to 4,200.
Six of the new cases were identified after the daily cut off, which means they will be included in Tuesday's official numbers.
Acting Victorian Premier James Merlino said the state was facing a "very significant" challenge, with a "small number of cases infecting a large number of contacts".
"I want to be very clear with everyone, this outbreak may well get worse before it gets better," Mr Merlino said.
The number of public exposure sites swelled to 279 locations across the state on Monday, with a number of grocery stores in inner-west Melbourne added to the list along with the Arcare Maidstone aged care facility. The full list of exposure sites can be found on the .
The five cases officially recorded for Monday include a second worker at Arcare Maidstone, who had not received her first dose of the vaccine because she was on leave during the rollout, a resident and the son of the worker who tested positive on Sunday.
The resident, a woman in her 90s, has been transferred to hospital for monitoring and has so far displayed mild symptoms. All other 75 residents and staff at the facility have tested negative to the virus.
An Arcare spokesperson confirmed 53 of the facility's 76 residents had consented to receive the Pfizer vaccine and had so far received one dose.
All workers at the facility would be offered their first or second dose on Monday, they said.
Speaking to reporters later on Monday, Federal Health Minister Greg Hunt said the question of whether it should be mandatory for aged care workers to be vaccinated is under "review".
"In relation to mandating for aged care workers, that had been previously looked at by the chief health officers of the states, along with the Commonwealth," he said.
"The prime minister and myself have asked the medical expert panel to review that decision - that was not recommended at the time.
"We have asked the medical expert panel to review precisely that question."
No decision has been made on whether the state's seven-day "circuit breaker" lockdown would be extended on Thursday, Chief Medical Officer Brett Sutton said, describing the situation as a "day-by-day prospect".
"With more numbers today coming through and those really concerning settings, especially in aged care, we are neck and neck with this virus and it is an absolute beast," he said.
Aged care employee worked across multiple sites
Questions have also been raised over why the second aged care worker to test positive was allowed to work across multiple facilities.
It was revealed on Monday the employee had also worked at the Bluecross Sunshine aged care centre from 26 to 28 May, forcing it into lockdown.
Mr Merlino said the "good question" should be directed to the federal government, who are responsible for the private aged care system.
“The answer is, public aged care is the responsibility of the state government. Private aged care is the responsibility of the federal government," he said.
The Victorian government banned public aged care employees from working across multiple sites after the state's disastrous second coronavirus wave.
Health Minister Martin Foley said he welcomed the federal government's decision to reinstate a rule to ensure staff were only working across one site after it was withdrawn last year.
"You'd have to ask the Commonwealth what the reasons as to why they didn't continue that policy which I understand now they have re-established," he said.
The federal government started funding aged care providers across Melbourne to support single-site working last week.
Federal Aged Care Services Minister Richard Colbeck said “single-site funding support” for Victorian areas impacted by COVID-19 was triggered on 27 May with the federal hot spot declaration and would be available until at least 10 June.
“This will support residential aged care providers to implement single-site workforce arrangements,” he said in a statement to SBS News.
"The grant funding will be available for out-of-pocket costs incurred during an initial two week period ... if the hotspot declaration is extended, these arrangements will also be extended."
Mr Hunt defended the decision not to enforce the rule earlier, saying it came amid a "very recent but rapid phenomenon".
"It's only in the last week that we have seen that community transmission," he said, adding it is a situation affecting the "absolute minority of staff".
“The advice in the greater Melbourne region is it is approximately 4.7 per cent of staff who have worked across different sites," he said.
"But the safety of residents, including vaccination testing, clinical first responders, coverage for those ill and the capacity for search workforce … this is the reason why the authorities had previously not made a change, it is very much something that could be done under public-health orders at the state level.”
Mr Sutton said the risk of transmission across aged care facilities needed to be "minimised to the fullest extent possible", describing the practice as "massively risky".
"It is a risk wherever it occurs, it doesn't matter if it's public or private, but the question of how it is effectively enforced, supported financially or otherwise, is a question of policy," he said.
Arcare Maidstone was placed into lockdown on Sunday and residents were isolated after the first staff member, a woman in her 50s, tested positive for the virus.
The Altona woman, one of five local cases reported on Sunday, tested positive despite receiving her first dose of the coronavirus vaccine on 12 May.
Contract tracers have so far been unable to determine how the worker contracted the virus, making her a "mystery case".
It is possible she was infectious during shifts on Wednesday and Thursday.
