The infected Melburnians live in the suburbs of Mitcham, Mentone and Hallam, all of which are in the east of metropolitan Melbourne.
The infected people and their close contacts have been placed in isolation with contact-tracers interviewing them about their movements late on Wednesday.
They will be retested to ensure they had not returned false positive tests. It is not yet clear whether the cases are in any way linked, or if they were exposed to people from interstate.
A list of several sites that were visited by the infected people was expected to be released on Wednesday night by the Victorian Health Department.
The growing Sydney outbreak has led the Victorian government to expand the NSW “red zone”. In a statement, the Health Department announced that people from the Blue Mountains and Wollongong regions would be barred from entering Victoria from midnight on New Year’s Eve.
“Anyone who has been in or visited the Blue Mountains or Wollongong regions from December 27 will have until 11.59pm on December 31 to enter Victoria,” the statement said.
“Anyone intending to return to Victoria from these areas between midnight tonight and 11.59pm on December 31 must apply for a new travel permit through Service Victoria, must get tested within 24 hours of returning to Victoria, and must self-quarantine at home for 14 days from when they last left the region.”
“Nobody who has visited these areas will be able to enter Victoria after December 31.”
The Victorian border with NSW remains closed. No one who has been to the Northern Beaches area, Greater Sydney, and the NSW Central Coast in the past 14 days is permitted to travel south of the border.
Earlier on Wednesday, one new case of coronavirus was reported in Victoria – a woman in her 20s who is in a quarantine hotel. Before the three local cases were announced, Wednesday was the 61st day in a row of no local cases in Victoria.
In addition to the three fresh coronavirus cases, there are seven active cases in hotel quarantine, and a 15-year-old girl who travelled from a NSW red zone and is in isolation at home after testing positive.
NSW recorded 18 new local coronavirus cases on Wednesday, including three without links to known clusters. Nine were linked to the Avalon cluster and six were linked to a new cluster in Croydon in Sydney’s inner west.
Police Minister Lisa Neville said the state government was “nowhere near” making a decision about when the border would reopen to Sydneysiders.
Ms Neville said there would be many different factors to be considered in relation to border rules, including case numbers and other state’s restriction levels.
“It’s a day-by-day proposition, we’re not in a position to contemplate opening the border,” Ms Neville said on Wednesday morning.
Victoria’s commander of testing Jeroen Weimar said it was too early to know when Victoria would reopen its border with NSW.
“If you look at what we did with South Australia when we had the Adelaide cluster that was a much smaller cluster, only around 20 or 30 cases at the end of it, and really brought up short, much more quickly. And we still allowed 14 days from the last exposure site before we reopened the border at that particular time,” Mr Weimar said.
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Paul is a Victorian political reporter for The Age.