The ACT has recorded 12 new cases, taking its outbreak to 94 after health authorities identified a duplicate infection.

All but one of the new cases are linked. One person is in hospital, but they are stable and don't require intensive care.

"I'm worried about under-16s, I'm worried about what we're seeing at the moment," Mr Barr told reporters on Friday.

Of Canberra's cumulative cases, 43 per cent are in children and 46 per cent in people aged between 18 and 44.

More than 250 exposure sites include schools, early learning centres, nightclubs and pubs, TAFE campuses, the city's light rail and bus routes as 20,372 people quarantine.

The chief minister criticised the federal government for not providing a heads-up it was expanding Pfizer eligibility for everyone between the age of 16 and 39

"This was announced with no advance notice given to states and territories or any information on the vaccine supply that would be necessary for this to happen," Mr Barr said.

Territory vaccination clinics are booked up until mid-October even through over-16s will become eligible for Pfizer nationally from August 30.

"The thing that's holding us back is available vaccine supply," Mr Barr said.

The Australian Institute of Sport arena will be turned into mass vaccination hub so under-40s can register for Pfizer when it's available.

"That's the crucial bit of information that we are waiting on," Mr Barr said.

He also questioned the federal goal of achieving vaccination coverage of between 70 and 80 per cent and wanted more clarity about what this meant.

"The vaccine is not immediately effective. Once it's jabbed into your arm. It takes several weeks for it to reach effectiveness," Mr Barr said.

"When we talk about 70 or 80 per cent, we must talk about when the vaccines become effective.

'Targets are not reached on the day of vaccination, it takes time."

The federal government earlier warned states and territories not to expect the same level of financial support for lockdowns once more than 70 per cent of eligible Australians are fully vaccinated.

In the ACT, nearly 35 per cent of the eligible population is fully jabbed.

Of people in their 30s, slightly more than 30 per cent have received one dose.

The rate falls to 25.5 per cent for those in their 20s and 10.3 per cent for teenagers aged between 16 and 19.

Mr Barr used Friday afternoon's national cabinet to raise concerns about vaccinating children.

"National cabinet needs to consider the rollout of a safe and effective vaccine programme for Australians aged under 16," he said.

The chief minister also flagged extra financial aid for businesses facing another two weeks of lockdown.

The details of the measures to be jointly funded by the ACT and federal governments will be announced in coming days.

Australian Associated Press