The one new case recorded in Victoria overnight was detected in metropolitan Melbourne, Premier Daniel Andrews has confirmed.

This case is linked to a known outbreak.

There are still seven active cases in regional Victoria, three in Greater Shepparton and four in Mitchell Shire.

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A testing blitz that has taken place in the Greater Shepparton area since cases were detected there on Tuesday has seen almost 5800 people screened for COVID-19.

Mr Andrews said he understood there were only a few hundred test results still to be returned.

He said 234 primary close contacts and 177 secondary close contacts of those who had tested positive had been identified and were isolating.

He again reiterated the call for Victorians to present for testing.

"Every single symptomatic Victorian needs to get tested as soon as possible," Mr Andrews said.

But there remain 17 cases for which the origin of infection is unknown.

Mr Andrews said these "mystery" cases remained a challenge and 17 was a "significant number".

Chief health officer Professor Brett Sutton confirmed a child who was being treated in hospital for COVID-19 was a mystery case.

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The premier has also commented on the 17 people who flew into Sydney from New Zealand, then onto Melbourne.

Mr Andrews said he was "very disappointed" this had occurred after writing to Prime Minister Scott Morrison to communicate that it was not appropriate for Victoria to join the trans-Tasman travel bubble with New Zealand.

He said the government was waiting to receive the passenger cards from Australian Border Force so the travellers could be located and brought up to speed on the state's coronavirus restrictions and rules.

But it was fortunate the travellers had come from a "low virus" part of the world, Mr Andrews said.

NSW and the Northern Territory have formed a travel bubble with New Zealand, under which travellers from New Zealand will not have to quarantine upon arrival.

Earlier

Victoria has recorded just one new case of COVID-19 overnight, the smallest increase in more than four months.

The last time the state detected one new case in a day was on June 5.

The small increase comes despite a testing blitz in Greater Shepparton, where three new cases were discovered on Tuesday.

As of Friday, there were 157 active cases across the state, seven of which were in regional Victoria.

Three of the regional cases were in Greater Shepparton and four in Mitchell Shire.

Two months ago, there were more than 6700 active cases across the state.

It has now been more than a month since a resident of central Victoria tested positive for COVID-19 - the last new, active case recorded in the region was in Greater Bendigo on September 11.

Premier Daniel Andrews said on Friday that the state remained on track to take "significant steps" out of lockdown, although confirmed the border between Melbourne and regional Victoria would remain.

He is expected to make an announcement about the changes on Sunday.

In the 14 days to Friday, October 16, the rolling 14-day average of new cases in Victoria was 8.6 - 8.1 in Melbourne and 0.5 in regional areas.

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