A coronavirus-prompted lockdown in Greater Sydney and surrounds including Wollongong and Shellharbour will be extended by a week after NSW recorded 27 new local COVID-19 cases.
"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," Premier Gladys Berejiklian said on Wednesday.
"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."
A fourth worker at a northwest Sydney aged care home has also been diagnosed with COVID-19 but has been in isolation for almost a week.
The premier spent much of Tuesday in discussions with health experts to decide "what next week looks like" ahead of a crisis cabinet meeting.
She told reporters on Wednesday the government had decided to extend the two-week lockdown on Greater Sydney, Wollongong, Shellharbour, Blue Mountains and the Central Coast by an additional week until midnight on July 16.
Students, returning from holidays next week, will mostly learn from home but schools will be open for children of essential workers.
Of the 27 new local COVID-19 cases for the 24 hours to 8pm on Tuesday, only 13 were in isolation for the entirety of their infectious period.
Federal Treasurer Josh Frydenberg on Wednesday said some NSW residents are eligible for the Commonwealth COVID-19 disaster payment but the government isn'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 also said COVID-19 transmission has occurred at Commonwealth Bank 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.