Victorian Health officials give update on 15 COVID cases, one who went to the footy

Acting Premier James Merlino said newer cases were workplace contact cases, with all cases, of the Indian strain of COVID-19, being in Melbourne.

"In the last 36 hours, we went from case one ... to identifying cases two to five ... to identifying seven to nine ... and then cases 10-12, the fourth line," he said.

"We know the first four cases are spread across three households, but within the same family unit, and yesterday we announced case five, who was a contact of case one.

"The 15th case we've just been notified of, and that will be included in tomorrow's numbers.

"What's clear is our public health teams are working very fast to test, trace and isolate this outbreak.

"These cases are linked and that's a good thing, but we are very concerned by the number."

There are a total of 23 active cases in the state and those 15 that were acquired in the community have prompted Victoria's largest ever testing day.

Victorian health officials are waiting for test results for about 200 people who have been identified as close contacts, and this will inform any further restrictions among other things.

Mr Merlino flagged no new restrictions additional to those relevant only to Melbourne flagged yesterday.

"I want to be upfront with everyone this morning - I cannot rule out taking some further action," he said.

"But we will update people. It's fair to say that the next 24 hours are going to be particularly critical."

The Victorian Health Department notified the community on Tuesday night that a person who tested positive attended the Collingwood/Port Adelaide game at the MCG on Sunday, May 23.

The person was sitting in Zone 4, Level 1 of the Great Southern Stand and those deemed close contacts will be notified by the DHHS and told to isolate.

CCTV is being used to determine if further advice is necessary.

"The AFL and the MCC have prepared for this moment," Mr Merlino said.

There are 80 of more than 100 close contacts across the cases identified so far that have so far tested negative.

Health Minister Martin Foley listed new exposure sites, which are across multiple Melbourne locations, and said yesterday was a record day for testing.

"Yesterday, we saw a record number of calls to our vaccine hotline," he said.

"That has been a strong sign people have got the message, if you are eligible to be vaccinated, please come forward."

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"The next 24 hours are critical and we'll have more to say about that on the basis of advice following on from the further work of (tracing) detectives."

Chief Health Officer Brett Sutton said some of those 15 cases had been out in the community.

"There are potential exposures there that relate to some days ago that are yet to potentially play out with new cases," he said.

"The next 24 hours will tell us if we've got further confirmed cases in primary contacts, 300 of which are known, and only 80 of which have returned results so far.

"Almost all of the remainder will come through today ... they're all factors we need to consider."

Mr Sutton said all 15 cases in the cluster were linked, but there is still a missing link with the original Wollert case, a man who returned from South Australian hotel quarantine and later tested positive.

There is a genomic link but no link has been drawn yet about how their paths crossed, following interviews.

Mr Sutton said the AstraZeneca vaccine was ensuring the U.K. were "getting over" their high cases.

"If you're eligible, please come forward now," he said.