As five million people in Greater Sydney endure a third week of lockdown, Deputy Premier John Barilaro is warning the situation could stretch out for weeks.

Greater Sydney and surrounds could remain locked down for weeks as authorities battle to deal with a dramatic spike in COVID-19 cases in the city's southwest.

Of the 112 new NSW cases reported on Monday, 84 emerged in southwest Sydney.

The area is now the epicentre of the outbreak and authorities are desperate to stop people going to work while unknowingly infectious.

Deputy Premier John Barilaro warned "we haven't hit the peak, my sense is we'll see similar numbers to yesterday ... maybe a tad higher".

As five million people in Greater Sydney endure a third week of lockdown he said the situation would likely stretch out for weeks.

"(I'm) not sure about longer than six weeks ... I think we're all certain it will extend beyond this week," he told Nine Network on Tuesday.

"It's the roller-coaster ride we're on."

Meanwhile, a joint NSW and federal government relief package to help people and businesses suffering financial hardship after three weeks of little or no income will be announced on Tuesday.

The federal government COVID disaster weekly payments will reportedly rise to $600 a week, up from $500, for those who have lost 20 hours of work or more.

The package will include JobKeeper-style increased cash flow payments for businesses to cover costs and wages, so long as no worker is sacked.

Meanwhile, school students start term three on Tuesday with pupils in Greater Sydney, including the Blue Mountains, Central Coast, Wollongong and Shellharbour learning from home for at least this week, while children of essential workers will be supervised at school.

Around 12,000 teachers and school staff will be prioritised to get vaccinated at a mass hub at Fairfield showgrounds from Friday.

NSW Education Minister Sarah Mitchell said both AstraZeneca and Pfizer vaccines would be available to school staff in three of southwest Sydney's local government areas that are COVID hotspots.

She said she had been advocating that all teachers be vaccinated for nearly a year but had been rebuffed because of a lack of supplies.

"We've prioritised teachers in these areas ... and I think this is a good first step," she told ABC Radio.

Ms Mitchell admitted it was challenging for teachers and parents to deal with home schooling but was unable to say how long hundreds of thousands of students would be learning from home - while flagging it was unlikely to end on Friday as originally anticipated.

"We want to give parents certainty. We've seen numbers go up significantly in the past two days and I think that has changed the settings," she said.

"We anticipate we will be able to tell parents and teachers within the next day or two what next week will look like."

NSW Health on Monday night flagged more than 20 new venues of concern and there are around 30 Sydney bus and train routes associated with confirmed cases of COVID-19.

Anyone who attended six venues in Sydney's southwest - including Ware Street Medical Practice, iMedic iCare Medical Centre, Neeta City Shopping Centre and Westpac - all at Fairfield, as well as various shops and 99 Bikes at Bondi Junction, are considered close contacts and must get tested and isolate for 14 days, regardless of the result.

And about 150 rough sleepers will get Pfizer COVID-19 vaccinations at the Reverend Bill Crews Foundation at Ashfield in Sydney's west on Tuesday.

"It's taken me months to secure these vaccines for the homeless and rough sleepers who we care for," Reverend Crew said.

NSW has recorded 678 COVID-19 cases in the community since June 16, when the Bondi cluster first emerged.

The AstraZeneca jab will be made available to all people aged over 40 at NSW mass vaccination clinics, and pharmacies will be able to administer it to that age group.

A new mass vaccination hub will also be established at Fairfield in southwest Sydney.