The Australian Technical Advisory Group on Immunisation (ATAGI) recommended to the government that the Pfizer vaccine is safe and effective for that age group.

In a statement, ATAGI said it recommended 12 to 15-year-olds should be added to Australia's COVID-19 vaccination program over time.

Some children in that age bracket with underlying health conditions were already eligible for the vaccine, but the latest advice expanded the rollout to include the entire cohort.

While Pfizer supplies remain limited, ATAGI recommends the timing of including adolescents needs to be balanced against access to vaccines for priority groups.

The states and territories are in charge of deciding when mass vaccine hubs can vaccinate children.

It comes a day after the state's booking system struggled to cope with an influx of 16 to 39-year-olds trying to book as soon as they became eligible.

Among those trying to book were tens of thousands of VCE students, who Premier Daniel Andrews had told earlier this week would be prioritised for vaccination before their final exams begin - which for some is less than six weeks away.

Frustrated Ballarat mum Kerri-Ann Batchelor spent hours trying to book a vaccine appointment for her son Luke, who is in year 12 at St Patrick's College.

The online booking system kept logging her out, the state booking telephone hotline cut her off, and after ringing local GPs and pharmacies the earliest Pfizer appointment she could get was November - after exams end.

Pfizer is currently the only vaccine approved for 16 and 17 year olds.

"These kids have been waiting 18 months to be able to do this ... and it's not that they don't want to it's matter of being available and it's not being made available to them in the best way.

"It's ok to announce this but in the end it's just words and it's not coming to reality.

"I want all kids vaccinated but they've got to come up with a way that all children will be vaccinated via the school system. How are parents of younger children going to get a booking when we can't even get bookings online for VCE students now?"

The current outbreak has impacted children more than previous waves. Of the 600 active COVID cases in Victoria, 128 are children aged nine or younger and 106 are aged 10 to 19. A further 107 cases are patients aged in their 20s.

"Following the final appropriate approvals from ATAGI, we would encourage students aged 12 and over and their families who wish to be vaccinated against COVID-19 to do so as soon as they are able. This will mean a confident step forward for our community in dealing with COVID-19 on an ongoing basis," said Ballarat Grammar headmaster Adam Heath.

"We know students learn best academically, socially and emotionally when they are able to physically attend school, and having a COVID-19 vaccination available to students aged 12 and over will enable our community to move forward together in a very positive way."

Mr Andrews said details on how year 12 students would be prioritised to receive the vaccines would be announced in the coming days.

"We have very successfully used priority lanes, and I think you will see that will be a feature of the plan that we announce ... quite soon. That approach has worked whether it is with healthcare workers, aged care workers, lots of different priority cohorts have been able to get there vaccine that way, so what works, works," he said.

The government will also engage with schools to possibly have groups of VCE students vaccinated at a particular place and time.

"It's got to be done in a sequential, logical way and school communities have to be part of that," he said.

Mr Andrews has also previously stated a goal that every student aged 12 or over should receive at least one dose of the vaccine before the end of the school year.

"The doctors tell us (one jab) reduces transmissions, provides 50 per cent to 60 per cent coverage, and that is a significant benefit. We think about so many young people moving around throughout the whole summer, that is one of those risks that we can dramatically reduce."

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