A fifth community case of COVID-19 has been detected in Melbourne's northern suburbs, Victoria's Department of Health announced on Tuesday.
On Monday, local health officials confirmed four people had tested positive for the virus in the city's north.
Earlier that day, the Department of Health announced that two probable cases were undergoing urgent retesting. It was later confirmed they were both infectious, with a further two close contacts also testing positive.
The fifth case, a man in his 60s, was reported to the department in the early hours of Tuesday and was formally entered into the system after midnight. He was identified as a contact of the first case and was urgently tested, which returned a positive result.
Health officials are linking the latest case to the outbreak in the City of Whittlesea, a local government area in Melbourne's outer northern suburbs.
The man is isolating, as are his household contacts.
Addressing reporters on Tuesday morning, health officials confirmed the man had started developing symptoms before the first case, indicating he could be a possible source.
"Importantly, he reports being symptomatic before Case 1 developed symptoms, meaning this could be a possible source case. A full investigation and interview process is underway and has to run its course," said Victoria's Acting Premier, James Merlino.
Following early investigations, the fifth case - like the four announced on Monday - has not identified any link to the exposure sites connected to a case in the northern suburb of Wollert two weeks ago.
This previously reported case tested positive for the virus on May 11 after returning from India on April 19. He contracted COVID-19 during his 14 days of quarantine at Adelaide's Playford Hotel.
Merlino added that genomic sequencing has found a close link between this case and the current outbreak, despite the new cases having no connection to the aforementioned exposure sites.
"Genomic sequencing has confirmed these cases originate back to the South Australian quarantine hotel," he said.
A full investigation into the source of the transmission is underway.
Restrictions announced for greater Melbourne
Based on the advice of public health experts, a series of measures are being introduced for greater Melbourne in light of the latest cases.
From 6pm on Tuesday (local time), private gatherings in the home will be limited to five visitors per day, and public gatherings will be restricted to 30 people. Face masks will need to be worn indoors, unless an exemption is granted. This requirement is for residents aged 12 and over.
Schools and workplaces remain open. Residents of greater Melbourne who travel to regional Victoria are able to do so, but the restrictions "travel with them", Merlino said. They will also be required to wear a face covering when indoors, even when outside of metropolitan Melbourne, unless an exemption applies.
The two cases who were initially categorised as "probable" are male relatives. The former, considered to be Case 1, had been tested for the virus on May 23 after developing symptoms. The latter is reported to be asymptomatic.
The additional two cases announced later on Monday are close contacts of the family - an adult woman and a preschool-aged child, who live in separate households, according to Health Minister Martin Foley.
The new cases bring an end to Victoria's 86-day streak without community transmission.
Update from NZ health officials expected later on Tuesday
An update from New Zealand health officials regarding the outbreak in Victoria is expected on Tuesday afternoon.
The office of COVID-19 Response Minister Chris Hipkins said a statement will be released at around 3pm.
Speaking to reporters, Prime Minister Jacinda Ardern reiterated that health officials are in close contact with their Victorian counterparts.
"You'll see some decision-making there around how they wish to manage the cases that they have," she said.
"We're just at the moment having a discussion as a team as to whether or not that will mean any flow-on impacts for two-way travel.
"I expect Minister Hipkins will give an update just a little later on today."
