People in NSW aged 40 to 49 will be able to register to get the Pfizer vaccine at a new mass COVID-19 vaccination hub that's opened at Sydney Olympic Park.

Around a million people in NSW aged between 40 and 49 could get a Pfizer COVID-19 jab at the new purpose-built vaccination hub at Sydney Olympic Park within weeks.

Premier Gladys Berejiklian announced the "exciting" development at the opening of the government-run Homebush hub on Monday.

"People aged 40 to 49 can register their interest in getting that Pfizer injection from 5pm today at nsw.gov.au," she said.

About a million people are in that age group, among the six million adults in NSW, she said.

For the first two weeks, the vaccination hub will be open to people in categories 1a and 1b - emergency and aged care workers, frontline workers and their families.

From Wednesday, anyone 50 or older can register to get the AstraZeneca vaccine at the hub from May 24.

The premier says it's still preferable that anyone 50 or older gets vaccinated by their GP who knows their medical history.

"If you don't have a GP or don't have access to a GP, or you find it difficult getting to them, you can book with us from 12 May and get your jab from 24th May," she said.

NSW Health said there were no new local COVID-19 cases recorded in the 13,768 tests undertaken in the 24 hours until Sunday night.

Coronavirus restrictions imposed across Greater Sydney last Thursday will remain in place for another week, except customers in shops will no longer be obliged to wear a mask.

Chief Health Officer Kerry Chant said while it remained unclear how an infected Sydney man caught the virus last week, the only person he's passed the virus on to so far has been his wife.

Genome sequencing confirmed he somehow caught the same strain of the virus that infected a returned US traveller.

"Unfortunately, we haven't found that missing link," Dr Chant said.

"We have tested everyone in close proximity to this gentleman, (so) the contact with the infectious person must have been very fleeting."

However, there could be undiscovered chains of transmission in the community, she added.

The NSW government expects the Homebush hub will be able to administer 30,000 COVID-19 jabs per week.

It will operate six days a week from 8am to 8pm in a state-of-the-art specially fitted out building.

Ms Berejiklian said NSW was ramping up the effort to vaccinate as many people as soon as possible.

"We're getting close to 700,000 but we've got a way to go," she said.

Health Minister Brad Hazzard noted it was 15 months since COVID-19 had arrived in Australia.

"It's been a war ever since. We're fighting back and this (vaccination hub) is our headquarters for the NSW Health team," he said.

The continuing restrictions mean that for the next week household gatherings remain capped at 20 people, masks are compulsory on public transport and in indoor venues such as theatres and aged care homes, and singing and dancing remains mostly banned.

Hospitality patrons are still not permitted to drink while standing.