Prime Minister Scott Morrison will meet state and territory leaders for an emergency national cabinet meeting, as COVID cases spike across the country just days before Christmas.

Leaders will meet on Tuesday for an update on the Omicron variant as cases mount in NSW, Victoria, Queensland and South Australia.

National cabinet was initially not scheduled to reconvene until early next year.

Mr Morrison said leaders needed to fine tune approaches to Omicron as more became known about the new variant. But he urged states and territories not to bring back travel restrictions this week.

“We would urge [state and territory leaders to] be calm, and consistent messages be given about travel arrangements and the requirements,” he said in Brisbane on Monday.

“It’s not unusual we would be meeting more regularly with Omicron being where it is.

“When we last met, we made some decisions, and it’s a good opportunity to update on all of that before Christmas.”

Experts have warned of a surge in virus infections in Australia during the Christmas and New Year period due to interstate travel and large gatherings.

The alarm comes as NSW Premier Dominic Perrottet continues to resist calls to bring back mask mandates  – and a survey shows people across Australia are already reconsidering Christmas and summer holiday travel plans.

NSW Health is urging people to keep wearing masks indoors, but Mr Perrottet remains reluctant to re-introduce mask mandates that were eased last week, saying it is time for “personal responsibility”.

“We are treating the people of our state like adults,” he said on Monday.

NSW had 2501 coronavirus infections on Monday – down 65 on Sunday’s record of 2566.

However, the number of people in hospital is gradually creeping up and health experts say cases will explode in January without a return to some restrictions.

There were no deaths on Sunday but there are 261 COVID-19 patients in hospital in NSW – up from 227. They include 33 in intensive care.

There has been a similar climb in Victoria, where 1302 cases were confirmed on Monday.

The state has 406 COVID patients in its hospitals, including 81  actively infected with the virus in intensive care and 43 on ventilators.

Its seven-day hospitalisation average has risen by seven to 387.

Dan Suan, an immunologist at Westmead Hospital, said the Omicron variant was much more contagious than any previous COVID strain.

“Sydney is sleepwalking into a catastrophic disaster in January if we don’t do something about it right now,” he said in a Facebook post.

“The only people that are really really protected from the Omicron infection are people who have a normal immune system and have been triple vaccinated.”

But, Mr Perrottet said case numbers were bound to rise ahead of Christmas and everyone was “likely to have a close encounter with COVID”.

“We are taking a balanced and proportionate response,” he said, adding the government would adjust settings if required.

“We need to stand strong. We are going to lead our nation out of the pandemic … we are ready,” he said.

“We need to also move away from fear and move to hope and confidence.”

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Mr Perrottet again urged people to vaccinated and get booster shots as soon as possible, saying state vaccination hubs would remain open over the Christmas break.

Of the 33 people in ICU in NSW, 26 were unvaccinated, proving that vaccination was the best protection against the virus, he said.

“Look at those numbers. They don’t lie. It is the best way to protect you and your family,” he said.

COVID spread puts travel plans on hold

Meanwhile, a survey commissioned by the Tourism & Transport Forum has found four out of five Australians have either cancelled or are undecided about their summer holiday travel plans, while one in two have no confidence in travelling interstate.

Chief executive Margy Osmond said the national survey of 1500 people revealed the concerns of three in 10 Australians had increased following the emergence of Omicron with the same number either cancelling or postponing their travel plans.

Seven out of 10 were waiting for more information before making a decision.

REX Airlines deputy chairman John Sharp said people had been cancelling Christmas travel plans.

“They’re either nervous about catching coronavirus or alternatively worried that they might be in a close contact to somebody who has got coronavirus and therefore they will be put into quarantine,” he told the Nine Network on Monday.

“When you travel, you are obviously going to be in very close contact with people and so the risks people are assessing are quite high. So we’re seeing cancellations now happening.”

There were 144,368 tests in NSW in the 24 hours to 8pm Sunday, and and 94.9 per cent of people aged 16 and older have had one dose of a COVID-19 vaccine. The fully jabbed rate is 93.4 per cent of people.

More than 81 per cent of NSW residents aged 12-15 have had one dose of a vaccine and 78.1 per cent have had both doses.

In Victoria there were 71,491 tests in the 24-hour period and 92 per cent of the population aged 12 and over is fully vaccinated.

However, record testing demand ahead of Christmas is putting Victoria’s testing system under pressure, with long lines on Monday morning.

At least 10 testing sites across Melbourne were temporarily shut at 9am after reaching capacity

There was a long queue outside the Bourke Street walk-in site, with people at one point facing a wait of three hours to get tested, before it closed as well.

Estimated wait times at other sites ranged from two hours to 15 minutes.

Victorian MP Ben Carroll said Acting Premier James Merlino and Health Minister Martin Foley were working “around the clock” to find solutions to cope with the influx of people needing tests.

-with AAP