Melbourne will go into its fifth Covid-19 lockdown tonight as health authorites work to contain two separate Delta strain clusters and a rapidly expanding list of exposure sites.

The planned lockdown, expected to run between three and five days, will mean Melburnians can only leave their home for essential reasons.

These include shopping for essential items, getting vaccinated, exercise, providing care and getting medical care.

It's understood schools will likely close however it's hoped the lockdown will be able to be lifted after the weekend, meaning parents will need to supervise little at-home learning.

Victoria's Covid-19 testing commander Jeron Weimar said today the state was dealing with "two separate incursions into Victoria over the last three or four days, two chains of transmission".

Five cases are linked to an outbreak the city of Hume, made up of four family members and one other contact after the family returned from a red zone and were not isolating.

The state's other cases are linked to Covid-positive Sydney furniture movers who worked at Melbourne's Ariele apartment complex while unknowingly infectious. There are 680 close contacts linked to that cluster, with 104 of those returning a negative result so far.

A list of exposure sites has been updated and includes the Melbourne Cricket Ground (MCG) after a Covid-positive man visited the stadium on July 10. Three positive cases are now linked to the MCG.

"You will appreciate we're dealing with a very dynamic situation here, a very rapidly moving situation here," Weimar said.

"What with we've got is two separate incursions into Victoria over the last three or four days, two chains of transmission, at least one is moving very actively and very aggressively across the state.

Transtasman bubble with Victoria

A decision is yet to be made whether a pause will be placed on the transtasman bubble with Melbourne, however Kiwis in the city should consider coming home, Covid-19 Response Minister Chris Hipkins said today.

Hipkins told Newstalk ZB host Mike Hosking this morning that New Zealand health officials were yet to receive enough information from their Victorian counterparts about whether a bubble pause was probable or not.

"But if you are sitting there thinking 'if a pause happens I can't afford to be stuck away from New Zealand', then it would be prudent to make your way home," he said.

"At this point we haven't got enough information from [Victorian officials] to make our own judgements on whether or not a pause may be necessary."

Hipkins said Victorian officials were giving their Kiwi counterparts updates every few hours and a decision would be based on those.

In a statement yesterday, Hipkins "encouraged anyone with concerns about the potential of a pause to quarantine-free travel, to organise to get home as soon as possible".

Travellers from Victoria would still need a negative pre-departure test, he said, and to fill out a travel declaration form including whether they had been to a location of interest.

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