Premier Gladys Berejiklian says it's "highly unlikely" that Greater Sydney's lockdown will end on Friday after 77 new COVID cases were recorded in a 24-hour period and a woman in her 90s died - Australia's first death from a locally acquired case this year.

"I'm anticipating the numbers will be greater than 100 tomorrow," the Premier said. "I'll be shocked if it's less than 100 this time tomorrow, of additional new cases."

33 of the new cases were out in the community while infectious. Some of the cases are described by the Premier as "quite historic going back five, six or seven days" before returning a positive test.

Ms Berejiklian said the community should be prepared for a lockdown extending into its fourth week.

"Given where we're at and given the lockdown was supposed to be lifted on Friday, everybody can tell it's highly unlikely at this stage, given where the numbers are," she said on Sunday.

"We've always been up-front about that."

Home learning for New South Wales school students could be extended because of the risk of transmission surrounding drop off and pick up time.

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A new risk from essential workers in south west Sydney who visit multiple sites, such as tradies, has been highlighted.

"It appears to be associated with large family groups in multiple houses, with many of the members of those households working in essential workplaces," Chief Medical Officer Paul Kelly said.

"Construction has been specifically mentioned, but they're out in the community and so that is the reason why it is it is spreading in those areas."

Testing being bolstered in those workplaces, while community leaders are understood to be helping health authorities.

Despite the growing numbers, the Premier is also sounding positive.

"I'm confident that in due course we will see things turn around because of the community response," she said.

It is understood the Federal Government is preparing to announce further assistance - under a national scheme - for New South Wales businesses, while broadening out current federal financial COVID-19 disaster assistance for individuals.

This is likely to be in concert with further assistance from the state government.

"I don't want New South Wales citizens to stress unnecessarily about their predicament," Ms Berejiklian said.

"Everybody's situation is different for everybody. I don't think there's a single person in this state that isn't going through some level of stress whether it's financial, whether it's just mental health or a whole range of other issues.

"Please know that the support you need will be there and we look forward to conveying that information in the next few days. But in the meantime, we just need everybody to stay home and I'm absolutely confident that we will get there because we've done it before."

Federal Treasury have put forward a number of options that the Prime Minister Scott Morrison is said to be working through.

Despite a request from the State Government, the Federal Treasurer Josh Frydenberg has ruled out a return to the JobKeeper wage subsidy regime.

Mr Morrison also held a meeting on Sunday to investigate mental health support for people in greater Sydney.

The Sydney woman in her 90s who died in Liverpool Hospital on Saturday was a close contact of a locally acquired case and had returned a positive COVID-19 test hours earlier.

She was not in aged care facility and it is believed she was unvaccinated.

"Regrettably, that person did acquire it within the household, within the home setting," Ms Berejiklian said.

"I can't stress enough that every time we risk breaking the rules or even just going about our business and not getting tested when we need to, the people whose lives and health that we're risking the most are those closest to us."

Citing clinical trials, Professor Kelly has encouraged anyone in Sydney waiting on their second dose of AstraZeneca to bring it forward earlier than the recommended 12 weeks.

"Earlier gives you less protection longer term but it gives you better protection now," he said.

"If you are in Sydney - only in Sydney - have a discussion with your GP to potentially bring that forward but that is a one-on-one discussion about that risk and benefit about that."

There are 52 COVID-19 cases in Sydney hospitals.15 people are in intensive care, including a teenager. Five people are being ventilated.

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