Victoria has delivered more doses than any other state as residents flood clinics in the wake of the state's fourth lockdown and an expansion of eligibility for jabs.

The commonwealth has told all states that they do not need to stockpile second doses, driving up utilisation rates in some states and territories to over 90 per cent.

It has forced Victoria to pause walk-in vaccinations at Pfizer hubs for the rest of the week in a bid to preserve supply for already-booked first and second doses.

ACTU secretary Sally McManus says the tight supply has meant many disability and aged care workers still can't get their first jab.

"These workers were in the 1A priority group, which was meant to take six weeks to vaccinate, mostly through in-workplace vaccination programs," she told AAP.

"It's June, the federal government has abandoned workplace vaccinations and now there are no shots available for anyone in that group under 50.

"These are the workers who kept our community safe through the pandemic, working with and caring for our most vulnerable."

Professor Catherine Bennett from Deakin University said there was always going to be a risk when eligibility was widened that supplies would be tight.

"We have now got our military capacity in operations and logistics looking after this nationally, so hopefully ... we can deploy the vaccine to exactly where it is needed," she told the ABC.

Labor frontbencher Bill Shorten described it as "more of a stroll out vaccine than a rollout vaccine".

Meanwhile, the government is hopeful of being able to make cutting-edge coronavirus vaccines like the Pfizer and Moderna jabs in Australia within 18 months.

Despite industry department officials telling a parliamentary committee earlier this month it could be three to four years before mRNA vaccines were made in Australia, Industry Minister Christian Porter told parliament the timeframe could be more like 12 to 18 months.

Mr Porter said four years would be an "absolute outside" timeframe.

The government last month gave companies eight weeks to lodge applications to manufacture mRNA vaccines.

Pfizer is being imported as one of two coronavirus vaccines being used in Australia, while Moderna supplies are expected to join the rollout later this year.

The mRNA vaccines teach cells how to make a protein to trigger an immune response.

Australian Associated Press