COVID-19 Quarantine Victoria has confirmed it held a “small function” for 60 staff at the View Hotel – one of three hotels used to quarantine Australian Open tennis players, officials and support staff – on Sunday.

Three days later a 26-year-old man – who worked at another hotel linked to the tournament – tested positive to COVID-19, ending the state’s 28-day run without community transmission.

“CQV held a small function to thank operational staff including team leaders, site and general managers for their considerable efforts in facilitating the complex quarantine program for the Australian Open,” a government spokeswoman said in a statement.

“Staff and guests observed the same public health safety requirements that all Victorians are required to adhere to when attending public gatherings.”

It is still unknown if the man is carrying a more-virulent international variant of the virus, with the results of genomic testing expected on Friday.

Late on Thursday, the health department confirmed it had identified 17 of the quarantine worker’s close social and household contacts.

Fifteen of those have tested negative so far, including two of his household contacts.

The final two results among the close-contact cohort are expected to be announced on Friday.

A further 600 casual contacts have also been told to isolate and get tested, as have 507 tennis players, officials and support staff.

Tennis Australia boss Craig Tiley said 495 of those had returned negative results, with just 12 still pending after being tested late on Thursday.

“It’s a timing thing,” he told Melbourne radio station 3AW on Friday.

“Hopefully in the next few hours we get the positive outcome that all are negative.”

Melbourne Park lead-up matches will resume on Friday following Thursday’s suspension.

Tiley said the Open would go ahead as planned from next Monday and there has been no change to crowd arrangements, initially capped between 25,000 to 30,000 each day.

Premier Daniel Andrews said the man had worked at the Grand Hyatt hotel and a review of security footage showed he was a “model employee” who correctly followed all safety procedures.

Deputy Chief Health Officer Allen Cheng said it was likely the man contracted the virus from a positive case in the quarantine hotel.

However, his case was not picked up as part of the state’s daily testing regime of hotel quarantine staff as he last worked at the hotel on January 29.

Instead, the Noble Park man went to be tested on his own accord after earlier developing symptoms.

“We are making sure that they are tested on their days off,” Cheng said.

“There will be a testing program for people that finish work.”

Meanwhile, the scare has prompted a number of states to introduce new testing requirements for people travelling from Victoria, including NSW, SA, Tasmania, Queensland and WA.