UPDATED 4.45PM 26/05/21 (AEST)

South Australia has become the first state to slap shut its borders to visitors from Melbourne as concerns grow about Victoria’s worsening coronavirus outbreak on Wednesday.

In a late afternoon briefing, SA Premier Steven Marshall said the border would close at 6pm (ACST).

“The only people exempted from this are essential travellers with the appropriate permit and also returning South Australians and returning South Australians will need to subject themselves to 14 days of quarantine,” Mr Marshall said. 

The Cohuna Kangas football and netball club posted to Facebook after a positive COVID-19 case attended one of its games in the Victorian border town on Saturday, May 22.

“We ask that people await official confirmation from the DHHS as to what the next steps are for people who attended the game on Saturday,” the club wrote.

Tweet from @sarahtlawrence9

NSW chief health officer Dr Kerry Chant also confirmed on Wednesday that several NSW residents had been identified as close contacts of the Melbourne cluster.

She revealed two had tested negative, while “a number of others” had visited one of the Melbourne shopping centres identified. However, by naming specific shops in the centre, Victorian contact tracers had “de-escalated the situation”.

Dr Chant urged NSW residents to watch the list of exposure sites.

“Check it at lunchtime, again this evening and again tomorrow. We are dealing with an evolving situation,” she said.

NSW requires declaration forms for arrivals from greater Melbourne and hasn’t ruled out extending that to include other areas of Victoria.

• See an updated list of Victoria’s exposure sites here

It came with Victoria poised on a knife edge as cases rose and authorities mulled the need for further restrictions.

Melbourne’s Herald Sun newspaper is reporting that Victorian authorities were locked in emergency talks on Wednesday afternoon, apparently considering a five-day lockdown. TND has not been able to confirm these details.

Chief health officer Brett Sutton earlier on Wednesday warned that any lockdown – if imposed – would be broad, rather than confined to the northern suburbs of Melbourne, where the cluster began.

“We’ve got significant spread of exposure sites at the moment so it’s not something that we would look to at a postcode level,” Professor Sutton said.

Acting Victorian Premier James Merlino said on Wednesday the next 24 hours would be “critical” for the city to avoid another lockdown, as six new infections were confirmed.

The latest cases are all close contacts of the City of Whittlesea cluster –  which has grown to 15.

Five of the six new cases are linked to a finance company in Port Melbourne, where one infected person works.

“It’s good that everyone is linked at this stage but we are concerned about the number and also about the kind of exposure sites,” Mr Merlino said.

“I cannot rule out taking some further action.”

All 15 cases have the B1617 COVD-19 variant, which originated in India.

• Victorian AFL teams in lockdown amid fears of rising crisis
• Second returned traveller’s infection sparks alarm

Genomic sequencing links the outbreak to the case of a Wollert man in early May.

On Wednesday, SA health authorities confirmed the man contracted the virus via aerosol transmission in hotel quarantine.

While confident authorities have “run down multiple generations of transmission”, Professor Sutton is concerned about the amount of time that positive cases have been active in the community.

“There are potential exposures there that relate to some days ago that are yet to play out in new cases,” he said.

By Wednesday afternoon, there were reports of panic-buying in Melbourne supermarkets, complete with photos of shelves stripped of toilet paper.

Tweet from @MatthewCoote

List of exposure sites expands

There are now more than 50 exposure sites across Melbourne and regional Victoria, including the MCG.

Health Minister Martin Foley said there was also “concern” about three bars listed as tier one exposure sites – Three Monkeys and the Somewhere Bar in Prahran, and South Yarra’s Circus Bar, all in inner-Melbourne.

The owner of Three Monkeys, Antony Harvey told the ABC he was confident of his bar’s comprehensive guest check-in system.

“There were a good 100-plus people who came through the venue over the course of the evening and we’ve been able to provide the DHHS team with our contact tracing already,” Mr Harvey said.

Three Monkeys self-identified as an exposure site via social media late on Tuesday night, urging punters to follow health advice and get tested.

Tweet from @threemonkeyscs

Mr Foley said of the 301 primary close contacts identified by Tuesday night, 80 had returned negative tests by early Wednesday.

A record 15,858 people received a COVID-19 jab at the state’s mass vaccination hubs during the same period.

• Outbreak proves vaccination ‘is a race’

Mr Merlino also flagged the possibility of expanding eligibility criteria for vaccines in Victoria.

“We’re just working through other details of what that looks like and getting advice from public health, but we are keen to explore what we can do about increasing eligibility,” he said.

Virus restrictions were tightening in Melbourne on Tuesday night, including gathering limits of five people at homes and 30 in public and mandatory masks indoors.

Queensland, Western Australia and the Northern Territory have all tightened restrictions for people travelling from Victoria but so far stopped short of closing their borders.

-with AAP