The NSW Premier says the community “can’t live reasonably” with the Delta strain of COVID-19, implying greater Sydney and surrounds will likely remain in lockdown until its outbreak is significantly curtailed.

It came as one of the country’s most senior doctors said it was vital NSW’s lockdown went on until the virus was eliminated from the community, otherwise it could lead to “disaster” – and NSW should consider tougher restrictions.

“There’s no alternative to elimination,” AMA president Omar Korshid said.

“Nowhere in the world has any community been able to live with Delta without very significant levels of vaccination.”

Dr Korshid said he hoped NSW could eradicate the virus and return to relative normal.

“But it will involve the government putting in very difficult measures if that’s what they need to do, in order to eliminate the virus,” he said.

On Friday, NSW Police will launch a major operation across the COVID-hit areas of south-western Sydney. Assistant Minister Tony Cooke said it would involve more than 100 officers and the aim was to be highly visible.

“We have a difficulty in south-western Sydney,” he said.

“Where we do not gather compliance, we will enforce – that is very clear.”

Premier Gladys Berejiklian has repeatedly described the Delta variant as a “game-changer” and echoed Dr Korshid’s view that vaccination was crucial to beat it.

“That is why it is so important for us to make sure that people follow the health advice,” she said on Thursday.

She appeared to back away from earlier comments by NSW Health Minister Brad Hazzard that hinted the state authorities might decide to give up the fight against the virus if people continued to flout lockdown rules.

“I think at some stage, if the individuals that we need don’t hear [NSW chief health officer Kerry Chant’s] message and don’t respond, then at some point we’re going to move to a stage where we’re going to have to accept that the virus has a life which will continue in the community,” Brad Hazzard said on Wednesday.

Sydney authorities remain concerned about people who are ignoring stay-at-home-orders.

Ms Berejiklian said her government had sought to be “bold and courageous” by keeping NSW open during the pandemic, but the Delta variant had changed the equation.

Until a significant proportion of the population was vaccinated, the variant could not be allowed to circulate, she said – meaning lockdowns remained necessary.

“NSW does want to open up, NSW wants to engage with the rest of the world, NSW wants to go back to normal life,” she said.

“But that depends on really getting our population, a substantial proportion of our population vaccinated so we can make sure that the hospitalisation rate and regrettably, in future times, the mortality rate is not beyond what the community expects.”

The lockdown of five million people across greater Sydney and its surrounds is scheduled to last until at least next Friday after being extended for a week.

Dr Korshid said lifting the lockdown too early could lead to “disaster”.

“We would be talking about long-term significant restrictions on people ‘s movements, from going in and out of lockdown, hospitals fill up with extremely sick people, and a devastating economic impact – not just on NSW but the rest of the country,” he said.

• WA threatens permanent ‘hard’ border to NSW

Dr Korshid said it would lead to “permanently closed borders” between NSW and most other states “which would have devastating impact on many families and businesses”.

“Elimination has been our secret to success with COVID-19, we have driven the virus out of our communities and reaped the benefits of that socially and economic, that lesson must continue to be learned,” he said.

Dr Korshid said, with the benefit of hindsight, NSW would “unequivocally” have been in a better position had it locked down sooner. But it was also the first Australian state to deal with a significant outbreak of the Delta variant.

On Thursday, Ms Berejiklian urged residents of greater Sydney and surrounds to further limit their movement and avoid mingling. There is a particularly focus on the Liverpool, Fairfield and Canterbury-Bankstown local government areas, where the virus is now most active.

She also urged eligible residents to urgently seek out vaccination.

About 9 per cent of the NSW population is fully vaccinated.

Second doses are likely to become easier to obtain for many in the lockdown areas, with the federal government recommending on Thursday that people seek out AstraZeneca boosters eight weeks after their first shot. That is a reduction from the current recommendation of a 12-week gap.

“That is consistent with medical advice … and given the risks to people of the outbreak in that area we believe it is important they get that second dose of AstraZeneca as soon as possible,” Prime Minister Scott Morrison said.

NSW will also get 300,000 extra AstraZeneca and Pfizer doses to help further boost its rollout.

The state had 38 new local COVID-19 cases on Thursday, the highest number of daily infections since the pandemic’s first wave. Among them were at least 20 people who were in the community for part or all of their infectious period.

Almost 400 people have now caught COVID-19 locally since June 16.

There are 11 people in intensive care in NSW, with three ventilated. The youngest person in ICU is in their 30s.