NSW has recorded another 136 new cases of the coronavirus and one death, as the lockdown of Greater Sydney approaches the four-week mark.

NSW's top doctor has declared Sydney's virus outbreak "a national emergency", after the number of new locally acquired cases in the state spiked to heights not seen since the first wave.

One death and 136 new locally acquired cases of COVID-19 were reported on Friday, almost four weeks after Greater Sydney and its surrounds were locked down in a bid to suppress the virus.

"This is a national emergency," the state's Chief Health Officer Kerry Chant said on Friday.

Of the new cases recorded to 8pm on Thursday, at least 70 were not in isolation for all or part of their infectious period.

The isolation status of another 13 people is under investigation.

The death of an 89-year-old man takes the NSW tally to 62 and the national death toll to 916.

"There is no doubt that the numbers are not going in the direction we were hoping they would at this stage," Premier Gladys Berejiklian told reporters.

"It is fairly apparent that we will not be close to zero by next Friday."

The premier flagged harsh restrictions would likely extend until October, when the national vaccination rollout ramps up.

"Where there are opportunities for us to open up, to ease restrictions, to let the economy undertake its necessary work, we will do that, but we will have a clearer view next week on what August, September, and October looks like for citizens around the state," she said.

Key to relaxing restrictions is better vaccination coverage, the premier said.

At a national cabinet meeting on Friday, she will push for the national vaccination strategy to refocus on Sydney - particularly the epicentre of the outbreak in the city's west and southwest.

Barely anybody with two doses of the vaccine is becoming seriously ill, she said, and even one dose reduces transmission and offers up to 30 per cent protection.

"We have been doing the heavy lifting for 18 months in keeping the virus at bay," she said.

"But in order for us to have our citizens live freely and openly, as well as other states to ensure that their citizens live openly and freely, we need to have a national refocus.

"The emergency we have in NSW is directly linked to the national vaccination strategy, but it also could impact other states."

Extra Pfizer doses would be especially critical in stemming transmission in critical workplaces in the hotspots, which are largely staffed by young people ineligible for the vaccine under the national scheme.

"These workplaces are not the hairdressers or the discretionary premises, they are premises that actually put food on the table for people in Sydney," Dr Chant said.

But Victorian Premier Daniel Andrews shot down the suggestion ahead of national cabinet, saying vaccines must be distributed fairly.

Stricter local lockdown orders will also be expanded to those living or working in the Cumberland and Blacktown local government areas, in line with orders already imposed on residents in the Liverpool and Fairfield districts.

No one can leave those areas unless they are a critical worker, which includes health and aged care workers.

Since lockdown was introduced on June 25 for four Sydney local government areas, and then expanded to the entire region the next day, infections have spread to Orange in the central west and interstate to Victoria.

Lockdown for Greater Sydney and its surrounds was set to end on July 30, and three local government areas - Orange, Blayney and Cabonne - in regional NSW are in lockdown until at least July 28.

But NSW health authorities are also concerned the virus has spread to northern NSW after fragments were detected at a sewage treatment plant serving Byron Bay, Wategos, Suffolk Park, Sunrise and Broken Head.

There are no confirmed cases in the area, so far.

However, Dr Chant defended the current restrictions.

"It isn't that the lockdown isn't working," she said.

"What we would have seen if it was not in place would have been skyrocketing, exponential growth in numbers."