The premier has expressed disbelief after learning the young woman was not vaccinated but continued to work shifts as a concierge stationed just outside the coronavirus ward of Prince Charles Hospital in Brisbane.

The 19-year-old tested positive on Monday but is believed to have been infectious in the community for about 10 days, and in that time worked two shifts at the hospital and went on a family holiday to Townsville.

Late on Tuesday, authorities confirmed she has the Delta variant, which is twice as contagious as the original virus and can be spread through fleeting contact that lasts just seconds.

One of her close friends and two of her family members are also now ill, and awaiting test results. The concierge also had contact with three other hospital workers.

Large swathes of the state are now under a snap three-day lockdown until 6pm on Friday, when it will be reviewed.

But given how contagious the Delta variant is, how long the worker was freely moving around Brisbane and north Queensland, there is a very real risk she has infected others in both locations.

The lockdown covers Townsville, nearby Magnetic and Palm islands, and all 11 local government areas in the state's southeast corner.

Every single one of Magnetic Island's 2500 residents has been told to get tested, and authorities have included Palm Island given it has a large Indigenous population that would be more vulnerable to the virus.

Townsville exposure sites include the airport, the city's popular Sunday markets, the ferry to Magnetic Island, and the entirety of the island.

Virgin Australia flight 369 from Brisbane to Townsville on Thursday, June 24, is also an exposure site along with the family's return flight, Virgin Australia, 374, on Sunday, June 27.

In Brisbane exposure sites include the hospital where the woman worked, Brisbane airport, a Woolworths at Sandgate, where the woman lives, and a local gym.

Premier Annastacia Palaszczuk promised an investigation into why the hospital worker was not vaccinated, and expressed exacerbation that unprotected staff continue to show up for work in high-risk environments.

"She should have been vaccinated, she was not. So the health minister will be overseeing that issue in detail," she told reporters. "I am absolutely furious about this."

The concierge was one of two cases of community transmission reported on Tuesday. The second was another miner who returned to Queensland from a Northern Territory mine where Delta has also been circulating.

But Chief Health Officer Jeannette Young considers him low risk because he's been isolating since very soon after returning to his home at Ipswich, west of Brisbane.

He is the second miner among a group of 170 who returned to Queensland from the mine. All are in isolation and are being closely monitored.

The premier acknowledged the hard, fast lockdown would cause pain but did not offer any new support measures for businesses who'll lose days of trading, despite pressure from the Opposition and the Chamber of Commerce and Industry.

She repeated demands for the federal government to dramatically slash overseas arrivals, including returning Australians, until vaccination rates are vastly higher in Queensland.

Meanwhile, Queenslanders aged under 60 have been told to stick with the Pfizer vaccine, after the prime minister declared all Australians, no matter their age, would be able to get AstraZeneca at GP clinics under an indemnity scheme.

The partial lockdown covers residents of Brisbane, Ipswich, Logan City, Moreton Bay, Redlands, Sunshine Coast, Noosa, Somerset, Lockyer Valley, the Scenic Rim, the Gold Coast, Townsville, Magnetic Island and nearby Palm Island.

Residents in those areas will only be allowed to leave home to shop for essential items, exercise, or receive or give medical care.

Masks remain mandatory and other restrictions have also been tightened including limiting funerals to 20 people, and weddings to 10 people, including the celebrant and couple.

As cases grow elsewhere Queensland will declare Perth and Peel in Western Australia and Darwin, Palmerston and Litchfield in the Northern Territory as hotspots from 1am on Wednesday.

Australian Associated Press