Victorian Premier Daniel Andrews has announced the state will enter a snap Covid lockdown from midnight on Thursday.
The "hard" lockdown will end on midnight on Tuesday and is “similar to or identical to what we did a couple of weeks ago," he said.
Mr Andrews said there is no other option and that the decision was “difficult”.
“I am not prepared to avoid a 5-day lockdown now only to find ourselves in a 5-week or a 5-month lockdown,” he said, adding that he can't "guarantee" the lockdown will end in five days.
There are now 18 Covid cases in Melbourne after Covid-19 Commander Jeroen Weimar announced a third infection linked to the MCG late on Thursday evening.
It follows his earlier announcement of two more local cases — and adult and child — who appear to be linked to a Maribyrnong man, who attended an AFL match between Carlton and Geelong at the MCG on Saturday and sat in the MCC members reserve on level 2.
There are now 75 exposure sites, 1500 primary close contacts, 5,000 secondary close contacts and 5,000 secondary close contacts.
"That is how fast this moves," Mr Andrews said, adding that contact tracers are "keeping pace with the virus, but not getting in front".
"We have no choice. We have to do this otherwise it will get away from us."
Victoria lockdown restrictions
Mr Andrews said that the same businesses that closed last time will close once again. Workers already deemed essential will remain so.
Residents will only be allowed to leave their homes for five reasons - to shop for food and essential items, provide or receive care, exercise, work or study if they are unable to from home, and to get vaccinated.
Masks will be compulsory indoors and outdoors.
All non-essential retail will close but essential stores like supermarkets, bottle shops and pharmacies will remain open.
Cafes and restaurants will only be able to offer takeaway.
No one is allowed to travel further than 5kms from their home, including for exercise, which has a two-hour time limit.
Childcare and kinder will stay open but schools will close, except for a small cohort of students.
Victorian locations where there is a risk you may have been exposed to Covid-19.
NZ closes bubble with Victoria
The growing Melbourne outbreak has prompted New Zealand to close the trans-Tasman bubble to Victoria for four days.
On Thursday afternoon, Covid-19 Minister Chris Hipkins announced a suspension of quarantine-free travel from Friday.
"We acknowledge the frustration and inconvenience that comes with any interruption to Trans Tasman travel, but given the ongoing level of uncertainty around transmission in Melbourne, this is the right action to take," he said.
The decision also bars anyone from travelling to New Zealand if they have been in Victoria from Friday.
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