"Pleasingly 17 of these cases have already been linked," Ms Berejiklian said.

"Two are still under investigation."

Ms Berejiklian said that the state had been braced for a surge in cases by Tuesday that did not eventuate, which she said indicated health advice regarding lockdown had been "on the money".

"NSW touch wood to date is in a situation where we still feel like we are very much in control of what is happening," she said.

"I'm very pleased with the health advice ... again, it's early days."

More than 67,000 people were tested in the 24 hours to 8pm on Monday as demand for screening surges.

NSW chief medical officer Dr Kerry Chant said one of the cases under investigation lived in Sydney's eastern suburbs while the other worked in that area.

"In terms of the cases, seven of the cases were in isolation for their infectious period," Dr Chant said.

"At the moment we are still seeing some cases that were potentially still in the community while infectious, but what we are hoping is that because of the lockdown the chances for that transmission will have been reduced considerably."

The cases include a Rose Bay Secondary College student, some cases linked to a Marrickville seafood wholesaler and others through a birthday party held in Hoxton Park.

Dr Chant said that anyone whose symptoms changed or evolved should consider re-testing.

"One negative test does not predict what may eventuate later that evening or in the next few days," she said.

Ms Berejiklian said she expected more cases to arise, "especially from household contacts". She urged anyone whose second AstraZeneca dose was pending to ensure they received the second jab.

She said conditions between the end of lockdown, slated for July 10, and reaching an 80 per cent vaccinate rate were on the government's mind.

"I want to assure people that the NSW government is already looking at what life will look like after the lockdown," she said.

"This Delta variant is very different to what we've seen before, and what we don't want is another lockdown.

"Until at least 80 per cent of our population is vaccinated, we can't have a conversation about what COVID normal looks like."

"Please don't let the lockdown stop you getting the vaccine. The only exception is if you have symptoms or are a close contact, please don't leave home."

IN THE NEWS:

Treasurer Dominic Perrottet confirmed at the Tuesday press conference that Dine and Discover vouchers would extend to the end of August as a result of Sydney's lockdown.

The 19 cases added to the 124 cases that had been linked to the Bondi cluster by 8pm on Sunday.

Lockdown continues for greater Sydney, including the Central Coast, while masks are mandatory indoors across regional NSW.

Ms Berejiklian has warned on Monday that numbers may fluctuate this week until the effects of lockdown began to show. Dr Chant instead recommended the public look to whether cases were linked to other known infections and if they had been in isolation.

The figures came after NSW Health named a number of venues of concern in Sydney with exposure windows extending back as far as June 21.

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