The Australian federal government has "paused" its plan to ease border restrictions from Wednesday, December 1, delaying the move by a fortnight as the world grapples with the new Omicron Covid variant.
This means fully vaccinated visa holders will not be able to fly into Australia without an exemption.
Australian Prime Minister Scott Morrison made the announcement on Monday night after a meeting of the Cabinet's national security committee was briefed on the latest information about Omicron.
At this stage, the easing of border restrictions will be delayed until December 15.
"On the basis of medical advice provided by the Chief Medical Officer of Australia, Professor Paul Kelly, the National Security Committee has taken the necessary and temporary decision to pause the next step to safely reopen Australia to international skilled and student cohorts, as well as humanitarian, working holiday maker and provisional family visa holders from 1 December until 15 December,'' a spokesman said.
"The reopening to travellers from Japan and the Republic of Korea will also be paused until 15 December.
"The temporary pause will ensure Australia can gather the information we need to better understand the Omicron variant, including the efficacy of the vaccine, the range of illness, including if it may generate more mild symptoms, and the level of transmission."
The standard rules, including that all arrivals to Australia require a negative PCR test and must complete traveller declaration forms detailing their vaccination status, will continue to apply.
Previous changes announced over the weekend include the reinstatement of home quarantine in some states that had dumped the requirement for international travellers.
Over the weekend Australia introduced temporary bans on travel to Australia from several African countries.
Anyone who is not a citizen or permanent resident of Australia, or their immediate family including parents of citizens, and who have been in African countries where the Omicron variant has been detected and spread within the past 14 days, will not be able to enter Australia.
The countries are: South Africa, Namibia, Zimbabwe, Botswana, Lesotho, Eswatini, Malawi and Mozambique.
Australian citizens and permanent residents arriving from these countries will need to go into immediate supervised quarantine for 14 days subject to jurisdictional arrangements.
In a statement, the Morrison government noted that the Australian Border Force retains discretion to allow people who are already in transit to enter, but these people will be subject to state based isolation requirements.
Under state public health orders, New South Wales and Victoria have already initiated testing and 72-hour isolation requirements for Australian citizens, permanent residents and immediate family members entering the country. In other states, 14 days of managed quarantine are required, and traveller cap arrangements are in place.
"Australia has a proven record of dealing with Covid, we have one of the lowest fatality rates, highest vaccination rates and strongest economies in the world," Morrison said.
"We will continue to take sensible and responsive evidence-based action, led by medical experts. This will ensure we can open safely, and stay safely open as we learn to live with the virus."
"Of course [Omicron] is concerning and that's why we're getting all the information we possibly can," Morrison told Sunrise on Monday morning.
"We moved very quickly on Saturday, this moved from a variance under investigation to a variant of concern within a very short period of time and we immediately put those extra controls in place on Saturday.
"The national security committee will be meeting this afternoon to consider December 1 decisions that are pending for migrants and students so we will review all of the information this afternoon and this morning."
In parliament, Morrison said the response would be "sensible, balanced and proportionate" and said he was working closely together with states and territories.
"We are listening to the best possible medical advice and evidence coming forward on the new strain,'' he said.
"It was this government that closed the borders, this government that made sure Australia was protected early on in the pandemic, and saved more than 30,000 lives."
But NSW Premier Dominic Perrottet urged political leaders not to offer a "knee-jerk" reaction that includes shutting borders.
"We need to open up to the world, we need to do so safely," he said.
Speaking on the Today show, Morrison suggested that even if the new variant was more transmissible, the question was whether or not it was more deadly.
"Case numbers of themselves are not the issue," Morrison said.
"It's about whether people are getting a worse illness or it's going to put stress on your hospital system. What we've seen in the states that have had these high case numbers is that the hospital impacts have been less than we anticipated.
"We have to live with this virus. The fact we've had a new variant is not a surprise. We've been saying all through the pandemic that new variants also come and we'll deal with them as they turn up."
The government's current recommendations on booster shots is also under review and Australians could be urged to get a third jab faster.
Australian Health Minister Greg Hunt said that if the Australian Technical Advisory Group on Immunisation recommended booster doses be brought forward, the government would follow that advice.
"We will, as ever, allow them to act independently and continue to follow their advice.
"But we're prepared with supplies."