Victorian health authorities are expecting more coronavirus cases after it was found that a Melburnian who tested positive for COVID-19 attended an AFL match with more than 20,000 others.

The infected person is from Melbourne’s north and one of nine active community cases linked to a cluster that has the potential to send the city back into a snap lockdown.

New alerts also include regional Victorian venues, and the outbreak has prompted other state leaders to further tighten border controls.

Among them is South Australia, which has banned travellers from Whittlesea – which is at the centre of this week’s outbreak – and imposed quarantine rules for Melburnians.

Fan was infectious while at Sunday’s match

Just before midnight Tuesday, the Victorian Department of Health revealed the positive case had attended the match between Collingwood and Port Adelaide last Sunday afternoon.

They sat in zone four, level one of the Melbourne Cricket Ground’s Great Southern Stand.

The health department is urging any of the 23,415 spectators who went to that game to monitor for symptoms.

Tweet from @rwillingham

It will, in the meantime, direct contact those who were seated in a bay between M1 and M16, and advise them to isolate until they return a negative test.

It will also review CCTV footage of the match to determine if those who were seated in other areas of the MCG should also get tested and isolate, regardless of whether they have symptomst.

Tweet from @VicGovDH

The department has reassured people that the AFL and Melbourne Cricket Club “have prepared for this situation in multiple simulations”.

They said fans’ contact information has been linked to ticketing data and QR codes, which will assist contact tracers.

The alert comes as a public health advisory panel mulls whether further restrictions will be required for large events.

That includes AFL games such as Friday night’s Marvel Stadium clash between the Western Bulldogs and Demons, and the RISING festival, which begins on Wednesday.

The Victorian Department is bracing for more coronavirus cases. Photo: Getty

Authorities to ‘chase down’ close contacts

A hair salon in Bendigo and a tavern in Axedale, both in central Victoria and attended by a coronavirus case, have been added to the growing list of COVID-19 exposure sites.

Four more infections were confirmed on Tuesday afternoon after a man in his 60s returned a positive result earlier in the day.

• Click here to check Victoria’s exposure sites

Authorities believe he was the source of infection for the previous four reported on Monday, meaning the outbreak investigation has moved further “upstream” and is closer to finding the missing link with the Wollert case.

Victoria’s chief health officer Brett Sutton warned there might be further cases on Wednesday, although 84 of 168 primary close contacts have so far tested negative.

“We have to chase down every single close contact … but it’s certainly not out of control,” he told ABC Radio Melbourne on Tuesday.

The following restrictions are in place for Greater Melbourne:

• Home gatherings limited to five visitors a day, public gatherings limited to 30 people;
• Mandatory masks indoors for people aged 12 and over;
• Schools and workplaces remain open, as do shops, cafes, restaurants and pubs;
• No changes to current density limits;
• People from greater Melbourne can travel to regional Victoria, but their restrictions travel with them;
• Hospital and aged-care visitor restrictions to apply across Victoria;
• Public health advisory panel to decide whether events such as AFL games and the RISING festival can go ahead;
• Ticket sales for round 11 and 12 AFL games suspended ahead of the panel’s advice.

Across Australia, other states and territories have responded to the Melbourne cluster by introducing their own travel rules.

Australian Capital Territory

• Anyone in Canberra who has been in Melbourne within the past 14 days must complete an online declaration form by 6pm Tuesday;
• Greater Melbourne arrivals in the fortnight to May 24 who have been to an exposure site must get tested and quarantine for 14 days;
• Non-ACT residents who have been to an exposure site cannot enter the ACT without an approved exemption.

NSW

• Any greater Melbourne arrivals must fill out a travel declaration form;
• Restrictions on arrivals who have been in the City of Whittlesea;
• Any arrival from May 10 who has been at an exposure site at a time listed must contact NSW Health immediately.

Northern Territory

• Testing and quarantine rules apply, depending on when travellers arrived from Victoria and which exposure sites they visited.

Queensland

• Anyone who has visited a Melbourne exposure site must quarantine for 14 days from 1am Wednesday;
• Anyone already in Queensland who has been to one of the sites must be tested and quarantine;
• Queenslanders urged to reconsider their travel to northern Melbourne suburbs.

South Australia

• Travellers from the City of Whittlesea must not enter (except for essential reasons);
• Anyone entering from greater Melbourne (except those who transited through from SeaLink) must go into self-quarantine until they have a negative test result;
• Any Victorian arrivals before May 24 at 8.25pm who have visited an exposure site must get tested multiple times, quarantine for 14 days and wear a face mask;
• After 8.25pm on May 24, anyone who has visited an exposure site cannot enter SA.

Tasmania

• All recent arrivals from Victoria being contacted;
• Any arrivals who have visited the exposure sites at designated times must isolate and get tested;
• Anyone intending to travel to Tasmania who has been to an exposure site cannot enter the state, without an exemption. They must quarantine for 14 days;
• Anyone who has been in Melbourne, and especially Whittlesea, since May 5 is urged to monitor for virus symptoms.

Western Australia

• Anyone who has visited an exposure site should be tested and quarantine for 14 days from the date of exposure;
• All other Victorian arrivals from May 6 should stay vigilant for symptoms.

New Zealand

• Three-day suspension of the travel bubble from8pm Tuesday (NZ time).

-with AAP