Premier Gladys Berejiklian confirmed the current five-week lockdown will be extended until at least August 28 for Greater Sydney, the Central Coast, the Blue Mountains, Wollongong and Shellharbour.
"In the last few days, it would have not been possible for us to get out of lockdown tomorrow or Friday and given also the advice, it would not have been realistic for the NSW government to make a decision in the next two weeks given where we are today," she said on Wednesday.
Of the 177 cases recorded in the 24-hours to 8pm on Tuesday, 68 were circulating in the community for all or part of their infectious period.
Wednesday marks the first day adults aged 18 to 39 can book an AstraZeneca jab at participating pharmacies while they can also book with NSW vaccination hubs from Friday.
In NSW, 30.4 percent of the population has now received their first dose of either Pfizer or AstraZeneca.
Some 13.1 percent of the population - 1.07 million residents - have received two doses.
Business NSW is calling on greater support for business as the lockdown hits hard.
"JobSaver is a good package that needs to be broadened and expanded as it only has a maximum of $10,000 in weekly support," chief executive Daniel Hunter said on Wednesday.
"This is too small for heavily impacted businesses, particularly medium and larger enterprises who employ more staff."
A new poll has found NSW voters are mostly happy with the premier's handling of the crisis, with 56 percent satisfied and 33 percent dissatisfied with her performance.
The poll of 1600 NSW voters on Monday by Utting Research was published in The Australian Financial Review on Wednesday.
Prime Minister Scott Morrison's handling of the national vaccine rollout left 62 percent of voters surveyed unsatisfied.
