Victoria authorities have confirmed a Melbourne man who tested positive for Covid-19 likely caught the illness in a hotel quarantine facility in South Australia.
Officials have made contact with hundreds of thousands of Melburnians in an attempt to narrow down the risk of a Covid-19 spread after the man visited multiple venues across the city.
The man tested positive to the virus following 14 days in hotel quarantine in South Australia, before flying to Melbourne and spending time in the community.
A Wednesday afternoon statement by Victoria's Department of Health and Human Services said genomic sequencing results have come back and that they "support the hypothesis that the Victoria case acquired Covid-19 in an interstate hotel quarantine facility".
It means Victoria hasn't had a locally acquired case of Covid-19 in 75 days.
SA Chief Public Health Officer Professor Nicola Spurrier said the results confirmed the Victoria case was linked to a case in the Tom's Court hotel in Adelaide.
She said investigations are ongoing, but those on level three of the hotel will have to quarantine for a further 14 days "out of an abundance of caution".
A CBD Indian restaurant, domestic Jetstar flight, Altona packing shed and Craigieburn and Flinders St stations were all listed among the most at-risk locations in Victoria following news of the case.
Victoria Health Minister Martin Foley said today that the government had contacted people who lived in Melbourne's northern and eastern suburbs, with testing also ramping up in those areas.
"We've sent out 396,000 text messages to communities who live near the exposures sites to get tested," Foley said.
"We've also increased the hours across every single one of our testing facilities and we've seen already this morning quite a strong surge in demand."
Foley said 18 patrons at Melbourne's Curry Vault Indian Restaurant and Bar had been tested, with a further 14 contacted and three of those returning negative tests so far.
A further 17 close contacts at Pact Retail Accessories in Altona North also received tests.
The man's three household contacts were in isolation and had all returned negative tests so far, Foley said.
The state reported no new local cases as of Tuesday evening.
"Yesterday we tested 21,461 Victorians, that's a very good figure and we've established more testing facilities in the northern and eastern suburbs based on a list of exposure sites," Foley said.
Contact tracers are also working to contact hundreds of Victorians who had travelled to and from Craigieburn and Flinders St stations on May 7, following an AFL game.
"We are working with both Metro services and the AFL, given it was the aftermath of the Richmond and Geelong game," Mr Foley said.
"We're working to get that message out through their clubs and get that message out to what we expect would be many hundreds of people on that train."
Passengers who were on the man's Jetstar flight JQ771 from Adelaide to Melbourne had also been contacted, but Foley said the risk of transmission on the flight was low.
"We've sent messages to those people to please come forward and get tested," he said.
"We think the likelihood of that flight being an acquisition flight is improbably, but this is out of an abundance of caution."
The infected Victoria man, in his 30s, returned to Australia from India on April 19.
The man returned to his Wollert home in Victoria on May 4, and developed symptoms four days later.
He was confirmed to have Covid-19 on Tuesday, sparking a "full public health response".
Hundreds of Victorians have been ordered to isolate after the man visited locations in Epping, Altona North and the CBD between Thursday and Saturday last week.
Alerts were issued on Tuesday for exposure sites in Melbourne's CBD, Epping and Altona North between Thursday and Saturday last week.
Three of the man's primary household primary contacts had returned a negative test result.
No new Victorian restrictions were foreshadowed on Tuesday, but authorities have urged people to follow the health advice, including wearing masks inside.
Amid the scare, Foley said Victorians and businesses were getting lazy with QR codes, which made it easier for contact tracers to track any potential exposure sites.
He said there were challenges in tracking those who visited the CBD restaurant as customers had not properly been implementing the use of the QR system at the site.
"This is a reminder that the quality and speed of the public health response is directly linked to record keeping that operators and customers use in the facilities," Foley said.
"The most important thing you can do when you come to a restaurant or facility is to check in."