Premier Gladys Berejiklian says the stay-at-home orders for Greater Sydney, Wollongong, Shellharbour, Blue Mountains and the Central Coast will now end at midnight on July 16, rather than Friday.

"This decision wasn't taken lightly," she told reporters on Wednesday.

"This Delta strain is a game-changer - it is extremely transmissible and more contagious than any other form of the virus that we've seen," the premier said.

"The reason why the NSW government has taken this position is because we don't want to be in a situation where we are constantly having to move between lockdown, no lockdown, lockdown, no lockdown.

"That is not a way to live and we want to give our citizens the best chance of staying safe and healthy but also making sure our businesses survive and thrive moving forward until the vaccination period is upon us."

School students due to return from holidays next week will mostly learn from home, but schools will be open for children of essential workers.

On the current timetable, schools across NSW will return to full face-to-face learning on July 19.

Of the 27 new local COVID-19 cases recorded in the 24 hours to 8pm on Tuesday, only 13 were in isolation for the entirety of their infectious period.

Ms Berejiklian confirmed the attention of health authorities was shifting to the Fairfield, Canterbury-Bankstown and Liverpool local government areas amid a surge in cases in Sydney's southwest.

NSW police issued 75 infringement notices on Tuesday.

Federal Treasurer Josh Frydenberg said some NSW residents were eligible for the Commonwealth COVID-19 disaster payment but the government wasn't considering any other financial support at this stage.

Workers can get payments of $325 or $500, depending on the number of hours of weekly work they have lost because of the lockdown.

Meanwhile, a fourth worker at SummitCare in Baulkham Hills has COVID-19, taking the outbreak at the facility to 10 people, including six residents.

However, the worker has been in isolation since Thursday. Some 130 staff members at the nursing home are isolating, with a surge workforce in place.

A SummitCare spokesman said on Wednesday that jabs were given to 24 residents on Tuesday, taking the facility's vaccination rate to 99 per cent.

The six COVID-positive residents - five of whom are fully vaccinated - are in Westmead Hospital as a precaution and are asymptomatic.

On Tuesday evening, NSW Health said COVID-19 transmission had occurred at the Commonwealth Bank branch at Roselands in Sydney's southwest.

Anyone who visited the branch at various times between June 28 and June 30 must get tested and isolate for 14 days, regardless of the result.

More than a dozen other health alerts were issued on Tuesday night for venues mostly in Sydney's west, as well as public transport routes.

Harris Farm at Bondi Beach, St George bank at Riverwood, McDonald's and Woolworths at Bonnyrigg and Big W at Menai are among the venues, with details and advice available on the NSW Health website.

Australian Associated Press