Chief Medical Officer Paul Kelly has also warned that a resident of a Sydney aged care facility is seriously unwell in hospital.

Six people have now been infected in the SummitCare facility in Baulkham Hills and transferred to the Westmead Hospital.

"Five of those were fully vaccinated and unfortunately the sixth one was not and I can report she is quite unwell at the moment, seriously unwell in hospital," Professor Kelly told reporters in Canberra on Sunday.

The Commonwealth government is expected to announce further assistance for NSW businesses, as the state government also prepares to stump up further support, while also providing aid for individuals and households.

But Treasurer Josh Frydenberg has repeatedly said the government won't be going back to a JobKeeper wage subsidy regime.

Treasury is understood to have put forward a number of options Prime Minister Scott Morrison is working through, although whatever is decided will be a national policy rather than being state specific.

NSW Premier Gladys Berejiklian announced the death of a women in her 90s alongside 77 new cases in the 24 hours to 8 pm on Saturday.

The Greater Sydney lockdown, that's already been extended to a third week, is looking increasingly unlikely to end anytime soon.

"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," Ms Berejiklian told reporters on Sunday.

She warned new cases could top 100 when she reports back on Monday

AMP Capital chief economist Shane Oliver has given a rough estimate of the cost of the Sydney lockdown as around $1 billion a week.

"However, if as appears increasingly likely the Sydney lockdown is extended much beyond the current three weeks, it will progressively cause more damage," Dr Oliver says.

"For example, another 4 weeks will see the economic cost blow out to $7 billion and take longer to recover from."

NSW treasurer Dominic Perrottet admits a further lockdown extension is going to be terribly challenging for businesses right across the state, and indicated further financial assistance would be available in the next few days.

"We have always said from the outset of this pandemic we will put the economy before the budget," he told Sky News' Sunday Agenda program.

The growing NSW crisis comes as the federal government embarked on a new advertising campaign urging people to get their coronavirus vaccine.

An ad being aired nationally - Arm Yourself - shows a series of bare arms with band-aids stuck on to signify they have had the jab.

Opposition Leader Anthony Albanese was unimpressed.

"We have been saying for some time that there needed to be a public information campaign but I'm not sure that this cuts it, frankly," he told ABC's Insiders program on Sunday.

"We were the best in the world in the campaign against AIDS, we've done drink-driving very well but after 18 months if this is the best they can do, they need to go back to the drawing board."

He said the government spent a lot of money advertising how well the recovery is doing but has spent little on advertising the vaccine rollout.

A second more graphic advert specifically commissioned because of the NSW situation, shows a young woman on a ventilator struggling to breathe in hospital.

However Australian Medical Association president Omar Khorshid said developments in Sydney should be enough for people to want to get vaccinated.

"I'm not sure if there is a bigger wake-up call for anybody around the country as just how severe this virus is and even in lockdown it is continuing to spread." Dr Khorshid told ABC television.

"That's why it is absolutely critical that people go out and get vaccinated, the only way to protect themselves and protect the country."

Even so, he said it was great to see the government actually spending some money on advertising the rollout and a simple message is the way for Australia to emerge from the pandemic.

Australian Associated Press