More than 36 hours after it was made public ACT Health is still unable to trace the outbreak's first reported case back to any previously known infections.

Commonwealth Games wrestler and bouncer Cedric Nyamsi on Friday outed himself as the Gungahlin man who had tested positive, declaring that he didn't know how he became infected having not left the ACT in the past three months.

Mr Nyamsi took aim at people spreading a rumour that he picked up the virus after travelling to Sydney in breach of health orders, telling social media users to stop "talking shit about me".

The 27-year-old, who is not vaccinated, told The Canberra Times that he had not spoken to police but was doing everything he could to help ACT Health get to the bottom of how he became infected.

"I am doing my best to help the ACT find out where I go the virus from, that is why I gave them my phone," he said.

"I want to help them to work out how to stop that virus because I don't want anyone to get it because of me or because of somebody else."

His comments raise the question of whether he had caught the highly transmissible Delta strain of the virus from another person in Canberra, and is not in fact the first case in the cluster.

Four of Mr Nyamsi's contacts have tested positive since his case was reported on Thursday.

READ MORE COVID-19 NEWS:

ACT Health did not rule out the possibility that Mr Nyamsi was not the first, or "primary", case in the outbreak when contacted by The Canberra Times late on Friday.

"Investigations are ongoing for all current active cases, and to the source of infection for this outbreak," an ACT Health spokeswoman said.

"It is one of the reasons that we acted quickly and decisively to put in place the lockdown."

Mr Nyamsi confirmed he was working as a bouncer at Fiction nightclub until 4.45am on Sunday - the first exposure site listed by ACT Health after the case was reported.

The spokeswoman said it was a concern that it had couldn't link the Gungahlin man nor the infected 14-year-old Gold Creek School student to any known cases in NSW.

"It is why it is critical that Canberrans take every precaution they can over the coming days and follow our lockdown requirements," she said.

"As further information becomes available on these cases, we will update the community."

ACT Chief Minister Andrew Barr on Friday said at that stage it was "entirely unimportant" how the man contracted the virus, as it would do "absolutely nothing" to assist authorities with the urgent priority of finding close contacts, testing them and advising the public of exposure sites.

"There is a time for those issues [establishing the source of the man's infection], but not today," he said.

Our coverage of the health and safety aspects of this outbreak of COVID-19 in the ACT and the lockdown is free for anyone to access. However, we depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support. You can also sign up for our newsletters for regular updates.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: