New South Wales has posted 30,062 new COVID-19 cases and 16 deaths from the virus, making it the state's deadliest day of the pandemic so far.
Meanwhile, Victoria has reported 44,155 new cases and four more deaths on Sunday.
In NSW, there are 1,927 people in hospital with the virus, up from 1,795 on Saturday. There are 151 in ICU, up from 145 a day ago.
In Victoria, 752 people are hospitalised with COVID-19, and 104 in ICU, with 23 ventilated. The numbers are also up from Saturday's figures, which showed 644 in hospital, 106 in ICU with 24 ventilated.
The latest case numbers in both states are slightly down from Saturday's, likely due to reduced testing numbers at the weekend.
But Victoria's caseload this weekend has been inflated by a backlog of cases registered via the state's new online rapid antigen test (RAT) reporting capacity. Some of the cases were up to a week old, with health authorities continuing to integrate the RAT numbers and ensure people who have taken a RAT and a PCR test are not counted twice.
People in NSW are expected to be able to register a positive RAT through the Service NSW app from mid this week in a bid to speed up its testing regime.
NSW registered 98,986 test results on Saturday, down on the almost 117,000 processed on Friday.
In Victoria, 22,051 of the new cases were detected through RATs and 22,104 were PCR test results, with the state processing 83,933 PCR tests on Saturday.
NSW to provide additional RATs ahead of 'challenging' weeks
NSW Premier Dominic Perrottet said his state was facing a "challenging three to four weeks" as he urged people to continue to get vaccinated, get their second shot or get their booster as soon as possible.
"If we look at ICU numbers, if we look at hospitalisation numbers, there is no doubt, no doubt, it is very clear, that vaccination is key to keeping you safe," he told reporters on Sunday.
More than 15,000 booster shots were administered across NSW in the last 24 hours, bringing the total given out to 320,000, he said.Mr Perrottet also said the state would procure an additional 50 million RATS in addition to the 50 million already provided.
NSW Premier Dominic Perrottet says it will be a "challenging" three to four weeks for Sydney. Source: AAP
The tests will be rolled out across the state, particularly to areas where there are vulnerable people as well as Indigenous communities.
The adequate provision of RATs will ensure kids can return school at the onset of term one, he said.
"These tests will be crucial to ensure that we get kids back to school day one, term one. We are finalising our back-to-school plans at the moment. This will be a core part of the plans getting kids back in the classrooms. We are completely committed to doing that."
"Those additional tests ... will be a very important as part of the new norm as we move through the next phase of the pandemic."
Mr Perrottet also announced a decision by NSW Health to provide an isolation exemption for asymptomatic close contacts who work in the critical food and grocery supply chain to return to work.
Wait for PCR results in Victoria 'starting to come down'
Victoria's COVID-19 commander Jeroen Weimar on Sunday said around 9,000 of the state's cases were from RATs done yesterday, which means the remainder were done in the days prior.
Mr Weimar also said authorities continue to catch up with testing demand and are aiming to turn PCR tests around faster, with about half now being returned within 48 hours.
"If you’re waiting for a PCR test result, please be assured that you will get a result, you will get a message from the lab at some point. It may not be as quick as we would like, but the times are starting to come down and you will get a swift result," Mr Weimar told reporters on Sunday.Thousands of Victorians have been waiting multiple days for PCR results, with because it was older than seven days.
Victorian COVID-19 Commander Jeroen Weimar speaks to the media during a press conference in Melbourne. Source: AAP
Mr Weimar apologised to those people and asked any who were still symptomatic to get another PCR or RAT test.
He said the introduction of RATs into mainstream testing was providing pressure relief.
"With the numbers I expect to get more and more representative as we go through the coming week. I expect the turnaround times to continue to drop progressively over the coming week."
Queensland delays start of school year
Queensland reported 18,000 new COVID-19 cases on Sunday, up from 11,174 cases on Saturday, with today's cases including 4,320 self-reported RATs. The state reported no new deaths.
There are currently 380 Queensland residents in hospital with the virus, with 22 in ICU. This is a jump from the 349 people hospitalised on Saturday, when there were 17 in ICU.
Premier Annastacia Palaszczuk said on Sunday that the school return will be delayed across the state from 24 January to 7 February, with the peak of the current wave expected at the end of January.
"It is not desirable to have our children back starting school during the peak of this wave," she told reporters on Sunday.
Students in Year 11 and Year 12 will start remote learning on 31 January. Students in Year 10 and below will make up for the delay by doing an extra week of schooling at the end of the year in December.
“This is delay but a necessary delay because of the wave that Queensland will be experiencing ... This is going to be a tough time of year for a lot of people, I thank them for their patience and their understanding," she said.
Ms Palaszczuk also announced changes made with immediate effect that will allow critical workers who may be quarantining at home but who haven't tested positive to continue to go to work in "certain circumstances".
"We need to keep the lights on, we need to keep the water supply going, we need to make sure our freight is moving and our food supplies go where they need to go to," she said.
Elsewhere in Australia, South Australia posted one death and 4,506 new cases on Sunday, up from 4,274 on Saturday. There are now 176 people in hospital and 18 in ICU, up from 164 in hospital and 16 in ICU reported the day before.
Tasmania recorded 1,406 new cases on Sunday, down from 2,223 cases on Saturday, with 15 people now in hospital with the virus.
The Northern Territory reported 481 new infections, down from 594 on Saturday. Hospital admissions have increased to 24 people, up from 17 yesterday.
The ACT posted 1,039 new cases, down from 1,305 cases the day before. There are 27 people in hospital, with 4 in ICU, up slightly from 24 in hospital and 5 in ICU on Saturday.
Western Australia reported one new local case of COVID-19 overnight. The person is a known close contact of two cases from the backpacker cluster and has been in quarantine so is not considered to have been infectious in the community.
Omicron peak 'weeks away'
The daily figures come as Australia's peak medical association warns extra support is needed to bolster Australia's healthcare system as it struggles to cope with COVID-19 amid skyrocketing Omicron cases.
Australian Medical Association president Omar Khorshid said with more people than ever before in hospital due to COVID-19 the system was "leaning on individuals ... without providing the necessary support".
"So elective surgery now ceased along east coast ... thousands of HCWs (healthcare workers) not at work... more in hospital with COVID than ever before and peak Omicron is weeks away? This is our health system 'coping'," Mr Khorshid wrote on Twitter.
He said GPs and private doctors "need help to help the rest of us", and called for restored telehealth access, more rapid antigen tests, and funding to help doctors cope with COVID-19 demand.
Mr Khorshid said "proper investment" was needed in public hospitals so they could deal with surges in demand.
New modelling shows NSW hospitalisations are expected to hit 4,500 in late January.
The worst-case scenario places the peak of the hospitalisation above 6,000, which is within the state's current capacity, Mr Perrottet has said.
He has fended off criticism concerning his decision to ease restrictions last month as the state's Omicron outbreak took hold, saying Omicron requires a different response.
"It is much, much less severe, and the approach we've taken is the right approach," he said on Friday, while reintroducing bans on singing and dancing at pubs.
"Clearly in the middle of a pandemic, when cases arise, that will dampen confidence but ultimately, the alternative is to lock down."
Government to launch vaccine program for children
A will be launched around Australia on Monday, with 3,500 kids booked in for the jab on its first day, Federal Health Minister Greg Hunt on Sunday.
He said there are three million vaccine doses available to this age group, which accounts for around 2.3 million children.
Mr Hunt said the fact that there were only 76 patients on ventilation around the country despite the significant number of COVID-19 cases was "very heartening" and said the most important challenge with Omicron was maintaining staff levels among health care workers.
"We have seen very low rates of significant illness," he told reporters.
"It is the workforce furloughing which remains the principal challenge at this point in time."
The minister also said the Commonwealth was looking to supply the states with 10 million RATs over coming weeks combined with additional tests provided to aged care facilities. Additional supplies will also be available through the private sector, he said.
"I have seen significant volumes coming in over the next few weeks," he told reporters.
He also said the booster program was on schedule, with 141,000 boosters administered on Saturday, which he said was "the highest Saturday since October".
It comes after the government announced on Saturday that workers who test positive to COVID-19 via RAT can from Monday access pandemic leave disaster payments of up to $750.
The move follows concerns of RAT shortages and retail mark-ups of more than 20 per cent over the supply price as demand for the home-testing kits escalates.
With additional reporting by AAP.