National cabinet opted to halve international arrival caps until at least next year to try and get on top of the highly infectious Delta strain of the virus which has plunged 12 million people into lockdown.

Prime Minister Scott Morrison has also pledged that there would be major changes in restrictions once a yet-to-be-agreed percentage of Australians were vaccinated.

The figure will be determined through scientific modelling expected to be completed within a month.

The number of people allowed to enter the country each week will fall from 6070 to 3035 after premiers sounded the alarm over the Delta variant.

During the reduction, which starts on July 14, there will be more government-facilitated flights to bring Australians to the Northern Territory’s Howard Springs quarantine centre.

Demand for the flights is expected to rise under smaller caps.

The four-phase reopening strategy will be linked to vaccination rates in what Morrison described as a “new deal for Australians today to get us to the other side.”

In the first stage, which Australia is now in, premiers and chief ministers agreed lockdowns would be used as a last resort.

Home quarantine is also expected to be trialled for fully vaccinated overseas arrivals, along with capped entry of students and economic visa holders.

The second phase would start when an undetermined percentage of Australians are fully vaccinated against coronavirus.

The government is still hopeful of offering all people over 16 a jab by the end of the year, despite just eight per cent of people being fully vaccinated.

That threshold would pave the way for eased domestic restrictions for vaccinated people, with lockdowns only expected in extreme circumstances.

More vaccinated people would be allowed to enter Australia and arrival caps for unvaccinated travellers would be returned to previous levels.

Morrison said stage three would involve treating coronavirus like other infectious disease including the flu with phase four the “back to normal” mark.

Hotel quarantine is also facing another review after 26 virus breaches since the start of the pandemic.

But the prime minister insisted the Delta variant was behind the decision to reduce arrival caps rather than using hotels, which has come under fire from experts.

“The Delta strain is more contagious and so we’re seeking to take precautionary steps to overall reduce the risk,” he said.

Morrison has been under fire since Monday when he highlighted a path for people under 40 to receive the AstraZeneca coronavirus vaccines.

Australia’s expert immunisation panel recommends AstraZeneca only for people aged 60 and above.

he prime minister rejected suggestions his loose language was to blame for fuelling more confusion around the rollout.

“ATAGI advice remains a preferential recommendation for Pfizer for under 60, but this does not preclude them from having AstraZeneca,” he said.

“Australians should have the choice to go and talk to their doctor and make a decision about informed consent about their own health.”

The federal government has given legal protection to doctors who administer AstraZeneca to younger people.

The key points from national cabinet were:

* Australia will reduce international arrivals by 50 per cent due to the risk of the Delta variant of COVID-19

* National cabinet has agreed to a four-phase plan to move away from lockdowns and restrictions once enough of the population is vaccinated

* The aim is to offer a vaccination to every Australian aged 16 and over by the end of the year

* The ultimate goal is to get to a position where COVID-19 is managed as an infectious disease like any other in the community

FIRST PHASE

* International intake will be temporarily reduced by 50 per cent by July 14

* Commonwealth will facilitate more flights to repatriate Australians, who will quarantine at Howard Springs in the Northern Territory

* Lockdowns to be used as a last resort

* Trials of alternative quarantine options including home quarantine for returning vaccinated travellers

* Hotel quarantine to face a second review to ensure health standards are being upheld

SECOND PHASE

* Kicks in once the national vaccination rate reaches a certain percentage of the population (to be determined by experts over the next month)

* Restrictions eased on vaccinated residents and lockdowns only used in extreme circumstances

* Inbound passenger caps restored to previous levels for unvaccinated travellers and more generous arrangements introduced for vaccinated travellers

* Possible capped entry of students and economic visa holders

* Introduction of some alternative quarantine arrangements

* Rollout of vaccine booster shots

THIRD PHASE

* COVID-19 will be managed like any other infectious disease, with hospitalisation and fatality rates similar to the flu or better

* No lockdowns, booster shots rolled out widely, no restrictions on vaccinated people and possible travel bubbles with other countries

FOURTH PHASE

* Uncapped arrivals of vaccinated people with no quarantine, and testing for unvaccinated travellers but no quarantine if negative