Hundreds of AFL fans who caught the train to and from the Richmond vs Geelong game on Friday night may have been exposed to coronavirus.
The AFL has contacted more than 50,000 fans who attended Friday's Richmond-Geelong match, amid fears hundreds may have been exposed to COVID-19 on the train.
The Craigieburn to Southern Cross service between 5.28pm and 6.07pm on Friday has been listed as a tier two exposure site, along with the Flinders St to Craigieburn service between 10.20pm and 11.05pm.
AFL fans who attended the Richmond v Geelong match on Friday night at the MCG have been warned they may have been exposed to Covid
Victoria's Health Minister Martin Foley said a large number of people may have been exposed on the train or at the station.
'It's in the many hundreds, particularly the later train back, because it was after the AFL game,' he told the media on Wednesday.
The AFL says it sent text messages on Wednesday morning alerting all of the 54,857 people who attended the match, while club members would also have received an email alert.
Authorities are also working with metro trains to contact passengers, and have urged anyone who was on the train to isolate and get tested.
The Covid scare comes after a returned traveller from India tested positive
Craigieburn and Southern Cross stations last Friday night have also been listed as tier three exposure sites.
The state has not recorded any further positive results after a Melbourne man tested positive on Tuesday, with more than 21,000 tests conducted in the past 24 hours.
It means Victoria has gone 75 days without a local case.
The man, in his 30s, flew into Adelaide from India via the Maldives and Singapore on April 19 before Australia's flight ban on returnees from India began.
Mr Foley also warned that people will soon face tough penalties if they don't use QR check in codes at venues, after some patrons at a new exposure site failed to use the system.
The new positive case dined out at the CBD restaurant Curry Vault on Friday, but many people who were there at the same time failed to use the QR system.
Fans who travelled to and from the Richmond v Geelong clash on the train may have been exposed to Covid
Authorities are chasing down patrons and staff at the restaurant, using takeaway records and financial transactions.
Of the 18 patrons that have been tested, three have so far tested negative, and another 14 patrons have since been contacted.
The Health Minister Martin Foley has described the incident as a 'wake-up call'.
'A number of patrons did use the QR code, but clearly not all of them,' he told the media on Wednesday.
'So far we have just had the one positive case, but the next day or two will be critical,' Mr Foley said.
There are a further 17 primary close contacts of the positive case, linked to shops in Altona North.
Victorians could return to tighter restrictions if evidence emerges the man infected others in the community.
Cars lined up at the Northern Hospital, Melbourne after a returned traveller from India tested positive
The department is awaiting the results of genomic testing to confirm how the man was infected.
After completing quarantine in South Australia at the Playford Hotel, he returned to his home in suburban Melbourne's Wollert early last week and developed symptoms on Saturday before testing positive on Tuesday.
SA authorities are examining whether the man contracted the virus before his arrival and had an unusually long incubation period, or caught it from a person in a neighbouring hotel room.
Victoria's Chief Health Officer Brett Sutton suspects the man picked it up in the hotel, and not in India or during his international flights.
All three of the man's household contacts have tested negative, with Professor Sutton describing this as an 'early encouraging sign'.
High exposure sites in Melbourne
TIER 1 (isolate for 14 days, regardless of result)
TIC Group / Pact Retail Accessories
Curry Vault Indian Restaurant and Bar
Indian Gate Spices and Groceries - Unit 14 C/560-590 High Street - 5pm and 6pm on Saturday, May 8
TIER 2 (Get tested and isolate until a negative test):
TIC Group - Rear warehouse section -214 Blackshaws Road, Altona North - All day, Thursday May 6
TIER 3 (monitor for symptoms)