Mystery surrounds a household of Covid-19 infections which has emerged at the end of Melbourne's Covid-19 lockdown.
The four new cases announced on Thursday have forced health authorities to tweak the newly-eased restrictions that will come into effect on Friday.
Deputy Chief Health Officer Allen Cheng told reporters the four cases were not existing primary contacts and had not visited any of the exposure sites identified from previous cases.
The four cases all live in the same Reservoir home in the city's north.
The first case identified as positive in the home was a male in his 80s.
"These new cases are really the strongest reminder that we are, by no means, out of the woods yet," Professor Cheng said.
The Department of Health's testing chief Jeroen Weimar identified the cases as a "new cluster".
He pleaded with Melburnians to check the list of exposure sites associated with the household which included Coles at Bundoora Square, and Bunnings in Thomastown.
"Please can I urge if you've been to any of those locations in those times indicated that you go and get tested today," he said.
"It's so important now with a new cluster that we establish as much information as we can about what may have been happening there."
Prof Cheng said masks would now be compulsory when leaving the home, instead of just indoor public settings.
"It's a small thing we can do to help prevent infection," he said.
Possible source of Queensland infections
He also said one of the two cases identified in Queensland from Melbourne had visited the Craigieburn Shopping Centre on May 23, making it a potential acquisition site. Nine cases are linked to the centre.
Prof Cheng said he was "anxious" over the highly-infectious Delta variant cluster, which still has a missing link to hotel quarantine.
"Obviously what I am anxious about is whoever gave infection to both these groups [the family and two Victorians in Queensland] is identified quickly and doesn't have the opportunity to transmit to other people," he said.
Greater Melbourne will exit lockdown at 11.59pm on Thursday night.
More to come.
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