Premier Daniel Andrews announced the AstraZeneca COVID-19 vaccine will be available to everyone aged 18 and above at all 50 of the state's vaccination hubs from Monday to help reach the target.

"It is the most important thing to come forward to get vax, to play your part, to protect not just yourself but the people you love the most and give us the freedom all of us want," he told reporters on Friday.

"Getting to 70 to 80 per cent (vaccinated), that is what we have to work towards and these one million jabs over the next five weeks are the best way that Victoria can make a contribution, not just to our state's fortunes, but to our national strategy."

Mr Andrews said there had been incredibly strong demand at the nine vaccination hubs where AstraZeneca has been available since Monday to people aged between 18 and 40.

Demand has been slower for people aged in their 50s and 60s, who are currently eligible for Pfizer at all state hubs.

Three more drive-through clinics will also be set up in Melbourne's southeast, southwest and northwest, following the popularity of the Melton site, which also opened on Monday.

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Mr Andrews expects 60 per cent of Victorians will be vaccinated by the end of September.

Victorian Chief Health Officer Brett Sutton said 11 of the new cases were linked to known outbreaks, while eight were in quarantine during their infectious periods.

The three unlinked cases are a delivery truck driver who lives in Wyndham Vale, a person in Middle Park and a person in Roxburgh Park, who is possibly linked to a school where an outbreak has recently occurred.

It's the third consecutive day the state has recorded mystery infections, with authorities also racing to find the source of four cases recorded on Thursday.

See the exposure sites here.

"We're looking at all possible linkages - schools, local sites visited in the acquisition period of the 14 days before symptom onset and any workplace connections for those attending on-site work," Professor Sutton said.

There are now more than 400 exposure sites across Melbourne and its urban fringe, including inner-city tram routes, an Australian Taxation Office building in Moonee Ponds and a VicRoads site in Hoppers Crossing.

Seven shops in the South Melbourne Market were listed as tier-one sites overnight after an infected person attended on Saturday from 1.30pm. The market will reopen on Friday morning following a deep clean.

It comes less than a month after the market was forced to close due to another COVID-19 outbreak.

There are two people battling COVID-19 in hospital, including one person in intensive care.

Latest data shows Ballarat is slipping behind other areas when it comes to the vaccine rollout, with Bendigo, Geelong and Warrnambool all seeing greater vaccination rates.

The news comes as Ballarat's vaccine rollout steps up to another gear, with people aged between 18 and 39 able to receive an AstraZeneca vaccination at the mass vaccination hub from Wednesday.

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