The infections are believed to be linked to the existing Brisbane cluster that began in a Portuguese restaurant and not Sydney's Bondi outbreak.

While the couple didn't attend the eatery, Chief Health Officer Jeannette Young says one is friends with people who did.

That person did not develop symptoms but got tested because they were working at Brisbane Airport's Direct Factory Outlet, which was earlier listed as an exposure site.

"We are going to deem them as infectious in the community from the 20th of June," Dr Young said on Sunday.

"They've been to a lot of sites throughout the community which we'll put up on our website, several gyms (and) several shopping centres."

The person's partner who lives in the same house tested positive and did develop symptoms.

"They've also been to a lot of venues, a lot of different sites, and they work in the Sunshine Coast," Dr Young said.

The Queensland Health website was updated with more than 20 new exposure sites later on Sunday, while details for two existing sites were updated.

If Brisbane's new cases are confired to be linked to the city's existing cluster, involving the Alpha variant, they would take that outbreak to nine known cases.

Meanwhile authorities are working to contact passengers aboard Virgin flights with a staff member who has since tested positive for the virus.

Five Virgin Australia flights on Friday and Saturday took passengers either to or from Brisbane, Melbourne, Sydney and the Gold Coast.

"Fortunately the flights were fairly empty because of all of the restrictions with Sydney," Dr Young said.

Millions of NSW residents have endured the first day of a fortnight-long lockdown, with residents of Greater Sydney, the Blue Mountains, Central Coast and Wollongong ordered to stay at home until at least July 9.

The lockdown came after the number of COVID-19 cases in the harbour city swelled by 12 to 80 on Saturday.

A positive case identified at a Northern Territory mine has also heightening concern in Queensland, with four linked infections already emerging and hundreds of potentially-exposed fly-in, fly-out workers in isolation in Queensland and Western Australia.

The man initially infected flew into Brisbane from Victoria before travelling on to the Northern Territory's Granites Mine, which is 540km northwest of Alice Springs.

While in Brisbane he stayed on the floor of a hotel previously linked to cases of virus transmission.

"Because he'd been on that floor he was asked to get tested, which he did, and that came back positive," Dr Young said.

All those staying on floor five of Brisbane's Novotel are now being moved.

Dr Young said there is "a lot happening" in the state, and urged anybody with symptoms to get tested as soon as possible.

"That is just critical," she said.

Queensland will also revert to previous venue density requirements and cap guests at private homes at 100 for the two-week duration of NSW's current restrictions.

Meanwhile Queensland recorded one additional case in hotel quarantine, bringing the active total to 40.

Australian Associated Press