NSW Premier Gladys Berejiklian has sounded a cautious note of optimism as Sydney’s coronavirus cases show early signs of steadying.

“It is early days and I don’t want to regret what I am about to say but we anticipated potentially a surge in cases by today,” Ms Berejiklian said on Tuesday.

“That could very well happen in the next few days but it demonstrates to us that the health advice has been on the money.”

With a bumper 67,000 tests in the 24 hours to 8pm Monday, NSW reported 19 new local infections on Tuesday. It followed 18 community cases on Monday.

Ms Berejiklian described the spike in test numbers as “an outstanding result”.

Of Tuesday’s cases, 17 were linked to known outbreaks.

NSW chief health officer Kerry Chant said seven of those were in isolation during their infectious period.

“What I want to see in progressive days is that we start seeing all of the cases being effectively isolated,” Dr Chant said.

“That will be a key indicator of success.”

She called on people who had visited or worked in the local government areas of Woollahra, Randwick, City of Sydney and Waverley to be particularly vigilant for symptoms.

NSW’s coronavirus clusters hit 149 on Tuesday.

But the early signs its outbreak might be steadying came with almost half of Australia’s population in a COVID lockdown, or about to head into one.

Tweet from @NSWHealth

Queensland

Queensland Premier Annastacia Palaszczuk ordered a snap lockdown of much of her state, saying “the risk is real, we need to go hard and fast”.

Millions of Queenslanders will be in lockdown from 6pm Tuesday after two new community infections.

Authorities are especially concerned about the second. A 19-year-old clerical worker at Brisbane’s Prince Charles Hospital tested positive for the virus after visiting a host of local venues and holidaying in the state’s north.

She regularly worked near the hospital’s COVID-19 ward – and was unvaccinated.

Ms Palaszczuk has ordered an investigation into why the worker hadn’t had a jab.

“Let me say, I am absolutely furious about this. We need to make sure that we are getting a population vaccinated right across the state,” she said.

Queensland has previously required only health workers inside COVID-19 wards to be vaccinated. But Ms Palaszczuk said that might have to be widened.

Tweet from @qldhealthnews

Chief health officer Jeannette Young said she was yet to link the woman’s case to any others.

Contact tracers are working on a detailed list of exposure sites, with the case prompting a lockdown of Queensland’s south-east, Townsville, Magnetic Island and Palm Island.

The woman visited several shops in the Sandgate area, where she lives, and worked at the hospital on Tuesday and Wednesday.

She also flew to Townsville on Thursday before travelling on to Magnetic Island for the weekend.

Dr Young said all 2500 people living on the island should get tested for the virus.

Test results are pending for two of the woman’s sick family members and one of her friends, who is also unwell.

Queensland’s other new local case is a worker linked to the concerning Newmont mine outbreak, who had already been isolating in Ipswich.

Northern Territory

The Northern Territory had two more local infections on Tuesday, with the wife and daughter of a mine worker testing positive.

Chief Minister Michael Gunner said NT authorities still expected further cases from the mine outbreak from central Australia.

“We are expecting more positive cases throughout this week,” Mr Gunner said.

“We are still very nervous, we’re not close to relaxing yet. There is still a lot to worry about, but the lockdown is working.”

• See the NT’s exposure sites here

South Australia

South Australian authorities remain determined to avoid a COVID-19 lockdown, introducing pre-emptive restrictions amid increasing infections elsewhere in Australia.

Premier Steven Marshall and chief public health officer Nicola Spurrier have urged people to get tested and vaccinated.

“It is a dangerous situation with this Delta variant. We’ve got to take the pre-emptive stance,” Mr Marshall said on Tuesday.

“We want to avoid a lockdown in South Australia.”

Western Australia

No new local infections were detected in Western Australia overnight. The Perth and Peel regions remain in lockdown.

Tweet from @MarkMcGowanMP

“These are challenging days for the country. The Delta variant is testing our systems and our community like never before,” Premier Mark McGowan said.

“I have faith, however, that we will crush this outbreak and save lives and jobs.”

Meanwhile, there were no new local cases of COVID-19 in Victoria, Tasmania or the ACT on Tuesday.

They have all imposed travel bans on the states and territories affected by the latest virus spread.

-with agencies