The national medicine regulator has given a green light for the domestic production of AstraZeneca's COVID-19 vaccine, paving the way for Australian-made batches to be released within days.

The Therapeutic Goods Administration has given its approval for CSL to manufacture the AstraZeneca vaccine at its two Melbourne sites in Broadmeadows and Parkville.

"Today's approval is a critical and very exciting milestone in Australia's response to the COVID-19 pandemic," the TGA said in a statement.

The approval doesn't extend to use, with the regulator still needing to review vaccine batch documents and test doses to ensure they meet manufacturing standards.

The TGA said receipt of the final batch release documentation from AstraZeneca was anticipated "imminently".

"It is anticipated that the first batches will be released in the next few days," it said.

"These will form the mainstay of Australia's COVID-19 vaccination program over the coming months, and complement imported vaccine supplies."

The announcement coincides with the next stage of Australia's vaccine rollout, which is facing further disruptions as heavy rain and flooding block roads in NSW.

The phase 1b rollout - for people over 70, Indigenous Australians over 55, those with a medical condition or disability, and workers deemed high risk - is due to start on Monday.

It comes as Sydney's Hawkesbury Nepean Valley, which includes Penrith, is set to cop its worst flooding in 60 years.

"Clearly there will be expected disruptions for many freight and logistic movements across NSW as a result of these floods. Vaccines will not be exempt from that," Finance Minister Simon Birmingham told Sky News'
Sunday Agenda program.

"So we are working with our freight and distribution companies who are getting the vaccine from point A to point B to just understand about what will be impacted"

NSW Premier Gladys Berejiklian says she has yet to briefed on any delays but assumes there will be distribution challenges because of the road closures.

"I'm not concerned, we will catch that up," she told reporters in Sydney.

Deputy chief medical officer Michael Kidd said distributors were doing all they could to ensure timely deliveries.

"Over 1000 scheduled deliveries have already been made and the remaining are ready to go as soon as roads are safe and practices are able to reopen and receive the deliveries," Professor Kidd told reporters in Canberra.

More than 250,000 virus jabs have been administered in Australia, a long way off the four million Prime Minister Scott Morrison said would be completed by the end of March.

There were just four COVID-19 overseas acquired cases recorded in Australia on Sunday, two in NSW and two in Queensland.

Prof Kidd said the result contrasts with the global situation where cases continue to be very high, with more than half a million reported in the past 24 hour-period along with almost 8500 recorded deaths.

Department of Health secretary Brendan Murphy is optimistic about the outlook, as long as most of the Australian population is vaccinated.

"I think life will return to normal, but I think we have just got to be patient," Professor Murphy told Sky News.

While the vaccines are safe, he said there are still a number of things that are not known about them including how long the protections will last, how good they are against variant strains of COVID-19 and whether people will need booster shots every year, like a normal flu jab.

Nonetheless, he expects the vaccine rollout will allow for a reduction of all restrictions and ensure state border closures are no longer required.