The decision to offer Pfizer to 16- to 39-year-olds from August 30 was a "captain's call" by Prime Minister Scott Morrison, according to ACT Chief Minister Andrew Barr.
Premiers and chief ministers weren't aware of the policy before it was announced, he said on Friday.
Mr Barr said while Mr Morrison usually informs the country's premiers and chief ministers before announcing a decision, sometimes it is only minutes beforehand.
"The Prime Minister has generally been very good at providing a heads-up. Sometimes we only get a few minutes, but at least he tells us. This one came completely out of the blue," he said.
"It's clear from the feedback across the federation that this one was a bit of a captain's call."
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Mr Barr said he wasn't opposed to the plan, but he did not have any information on how the vaccines would be rolled out.
"I'm not opposed to what he's announced, I just need to understand how we're gonna do it and we don't have any information about that," Mr Barr said.
"We didn't know anything about it. We hope to get more information and be able to answer all of the questions the community has."
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