Businesses will receive thousands of dollars in grants and the NSW Dine and Discover voucher program for state residents will be expanded as part of the package.

"We know that our lockdown ... has created much stress," Premier Gladys Berejiklian said on Tuesday.

"We don't want anyone to feel stressed during this lockdown that they won't be able to manage their household situation or their business situation."

Grants of between $5000 and $10,000 will be available to small businesses, depending on declines in turnover, during the health restrictions.

NSW residents will now have until August 31 to spend their Dine and Discover vouchers, which will also be able to be used on takeaway food orders.

Of the 19 new cases of COVID-19 recorded in NSW in the 24 hours to 8pm on Monday, 17 are linked to previous cases and two are under investigation.

One of the mystery cases lives in the eastern suburbs and the other works there.

Seven of the new cases were in isolation for their infectious period.

Ms Berejiklian praised the around 67,000 people who came forward for testing in the latest 24-hour as "outstanding".

Some 149 people have picked up the coronavirus locally since June 16, when the first case was reported at Bondi in Sydney's east.

Tuesday marks the third full day of a two-week hard lockdown for the Greater Sydney, Central Coast, Blue Mountains, Wollongong and Shellharbour regions.

Millions of people can only leave home for work that can't be done at home, to shop for essentials, for exercise, to seek medical care and for caregiving or compassionate reasons.

NSW Health has issued alerts for another ten venues visited by COVID-19 positive people.

They included Specsavers at Bondi Junction, McDonald's at Bondi Beach, Macquarie Bank in Barangaroo, Domino's Pizza Rose Bay, IGA Blaxland and the Meriton Suites Hotel at Mascot.

NSW Health has also alerted commuters who travelled on various Sydney trains and buses last week and Westfield Bondi Junction - the epicentre of the latest outbreak - remains of particular concern.

Those venues, plus scores more listed by NSW Health, have sent thousands of people into isolation.

More than 500 school students from South Coogee Public School are isolating after four of their classmates acquired the virus.

Another student, at Emanuel School in Randwick Sydney's east, attended school whilst infectious.

On Monday evening, a positive case was also uncovered in the Rose Bay Secondary College community, with around 1300 students and teachers ordered to self-isolate until further notice.

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