Disturbing photos have emerged of fans packed like sardines in the concourse and outside AAMI Park for the Wallabies' Test match against France last week.
Victoria recorded 22 new local coronavirus cases on the sixth day of its extended statewide lockdown on Wednesday.
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The current outbreak has been linked to two "super-spreaders" who attended sporting events while unknowingly infectious.
The first man is a resident of the Ariele Apartments in Maribyrnong, which was visited by a Covid-infected removalist crew from NSW on July 9.
The man did not know he was infected with the Delta variant when a day later he went for a drink with a friend at the Young and Jacksons pub in Melbourne's CBD, before heading to the Geelong-Carlton AFL match at the MCG.
Nine people seated in the MCC Members Reserve and five of their close contacts have since tested positive for Covid-19, as well as seven people linked to Young and Jacksons.
Among those to contract the virus at the MCG was a man in his 30s, who 30 hours later attended a Euro 2020 championship viewing party at the Crafty Squire in Melbourne's CBD.
The next day, he had dinner at Ms Frankie in Cremorne with 12 friends before heading to the Australia-France Test match at AAMI Park.
The man also did not know he was infected and was asymptomatic at the time.
Photos have since emerged of a concerning lack of social-distancing while fans attempted to get into AAMI Park.
According to the Herald Sun, authorities are said to be "furious" over a lack of crowd control measures.
Hundreds of fans were seen crammed together in close proximity outside Gate 7 as they awaited entry into the ground.
Three people at AAMI Park and one person at the Crafty Squire have since tested positive for Covid-19, sparking their own chains of transmission.
Premier Daniel Andrews said the two "super-spreader events" had proved the need for a statewide lockdown.
"The speed with which this has moved through the Victorian community confirms that we did the right thing to lockdown and it sadly confirmed that we need more time," he told reporters on Tuesday.
Victoria virus outbreak prompts stadium crowds rethink
The Melbourne Cricket Ground and AAMI Park have had their exposure site statuses expanded over fears of more "stranger-to-stranger" cases.
"We cannot make the whole of the MCG a tier-one site," Chief Health Officer Brett Sutton told reporters.
"Quarantining tens of thousands of people and overwhelming testing with tens of thousands of people, that would be an overreach."
Other sections of AAMI Park remain classed as tier-one exposure sites.
With more instances of "stranger-to-stranger" transmission, Prof Sutton is unsure whether Victoria will be able to return to the 75 per cent outdoor capacity crowd limit in place prior to the state's fifth lockdown.
He said public health officials were assessing other risk mitigation techniques for major sports crowds including harder sub-zones, staggered entry, rapid pre-event antigen testing and checking fans' vaccination status.
"I've always said that needs to be a national consideration. We shouldn't be going out alone on that," Prof Sutton said.
"But all of those things should be in play."
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