The government was in talks with the pharmaceutical giant, which had asked for initial approval for its vaccine from Australia's medicine regulator.

But Health Minister Greg Hunt has ruled out proceeding with the purchase at this stage because it is too similar to the AstraZeneca drug.

"The Janssen vaccine is an adenovirus vaccine, the same type of vaccine as the AstraZeneca vaccine," he said through a spokesperson.

"The government does not intend to purchase any further adenovirus vaccines at this time."

Johnson and Johnson also required a no-fault compensation scheme before it would sell vaccines to Australia, which the government was not committed to introducing.

Labor health spokesman Mark Butler said it was not good enough for the minister to announce his decision through a spokesperson.

Mr Butler wants to know the reasons behind the decision and greater accountability from the whole government on the vaccine rollout.

"This is the problem Australians and Australian businesses are having right now - the communication channels from the government have shut down," he told the ABC on Tuesday.

"We've got a prime minister that's retreated to Facebook and a minister who's making announcements through a spokesperson without clear background information."

Labor has spent months calling on the government to secure more vaccine deals, arguing most countries have five or six different options.

Scott Morrison has taken to Facebook to reassure Australians about the vaccine rollout.

Mr Morrison has abandoned all vaccine timelines and targets after medical authorities recommended people aged under 50 get the Pfizer vaccine instead of the AstraZeneca jab, which was the country's mainstay.

He claimed targets were not possible as COVID "writes its own rules".

"You don't get to set the agenda," he said.

"Rather than set targets that can get knocked about by every to and fro of international supply chains and other disruptions that can occur, we are just getting on with it."

Mr Morrison said Australia's current rate of 1.2 million vaccinations to date was comparable to other major countries.

But government figures show Australia's rollout, compared to 12 other nations, is running behind the UK, US, Singapore, Belgium, Italy and Germany.

Business groups have warned the strength of the country's economic recovery depends on the vaccine rollout.

They argue if the Morrison government is no longer willing to set timetables, it should at least set major vaccine milestones, so that businesses can plan for the future.

Qantas is closely monitoring the vaccine program as changes to the rollout threaten the resumption of international flights.

The government has abandoned its target of offering all Australians their first vaccine doses by the end of October.

Qantas was hoping to resume international services at that time.

Australian Associated Press