People under 50-years-of-age who are already booked in to get the vaccine for the next three days are being told to delay, unless it is the Pfizer jab.

Those getting the Pfizer vaccine are not affected by the postponement.

The state government has also confirmed it has not locked in any plans for extra "super-vaccination" hubs, including amy in Bendigo.

It has not announced plans for a high-volume Bendigo centre despite revealing plans for a new centre in Ballarat on Thursday.

Any decision to go ahead with future hubs is understood to depend on the supply of vaccines from the federal government.

Victoria is responsible for providing vaccinations to workers in health, emergency services and other critical industries and public sector aged care during the rollout.

A Bendigo hub for the vaccinations opened over a month ago in Stewart Street, but is different to high-volume sites.

Ballarat Health Services will manage its new high-volume site at Mercure Ballarat.

It is expected to open soon, a Department of Health spokesperson said.

"This site and another at Melbourne Showgrounds joins five existing high-volume centres across the state plus dozens more hospital vaccination hubs, sub-hubs, and outreach delivery services currently in operation or preparing to come online," they said.

"The majority of Victoria's nine hospital vaccination hubs are located in regional Victoria."

Ballarat and Melbourne's new high-volume centres join five other sites in Melbourne and Geelong.

Victoria is aiming to administer 300,000 vaccination doses by May 16.

Victoria was nearing the halfway-mark on Thursday with roughly 137,000 administered.

Australian health authorities are reviewing the AstraZeneca vaccine following one report of a blood clot side effect.

They say the shots can still be administered in certain cases if federal information can be provided, and if the benefits of the COVID-19 shots outweigh the risks.

State authorities have paused AstraZeneca shots until Monday, following an evening news conference on Thursday where prime minister Scott Morrison revealed health authorities' updated advice.

People who have already received an AstraZeneca vaccine without adverse side-effects should still receive a second one, health authorities recommend.

AstraZeneca shots have so far been the backbone of Australia's vaccine program rollout.

-With AAP

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