The spike in cases caused by Omicron is forcing states that had previously adopted Covid-zero approaches to confront their first major outbreaks since the beginning of the pandemic, with South Australia recording more infections per capita on Friday than Victoria.
On Friday SA recorded 688 new Covid-19 infections, with the state's premier, Steven Marshall, revealing about 70% of them were from the Omicron variant.
"What we are very concerned about is the very significant increase in transmissibility. We do have to take action," Marshall said on Friday.
The SA government has responded by overturning a ban on rapid antigen testing, as well as continuing with a number of restrictions that had been due to end on 28 December.
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In Queensland, where 589 new cases were recorded on Friday, the health minister, Yvette D'Ath, warned residents to "get ready for Covid".
But in New South Wales, where case numbers began to dramatically spike as a result of the Omicron variant earlier in December, early reports from some frontline doctors have provided reason for optimism.
On Thursday the state's premier, Dominic Perrottet, said emerging data from NSW suggested the Omicron variant was "five times less severe" than the Delta variant.
Chief health officer Dr Kerry Chant said evidence from both here and overseas indicated "infection with Omicron is likely to be milder than infection with Delta, with the risk of hospitalisation being about 60% to 80% less than for Delta".
That was supported by a UK government study released on Friday, which suggested the risk of being admitted to hospital was up to 70% less for people with Omicron compared to those infected with Delta.
General practitioner Ziad Basyouny helped to establish out-of-hospital care for Covid-19 patients in western Sydney during the Delta wave, and has continued to work in that team during the Omicron outbreak.
Basyouny was unequivocal about the difference in presentations between the Delta and Omicron strains, saying the latter had so far seen most patients develop "very, very minor symptoms".
"It's so apparent. Tomorrow I will have about 20 patients who are at high risk. Of those 19 will have no symptoms. It's so different to Delta. During Delta I'd call maybe 60 people a day and out of those all 60 would have symptoms," he said.
"People say it's too early to call it milder and I know it's too early for epidemiologists, but clinically I can't say anything else. I can't change the fact that these patients are presenting as less severe."
Despite that, the pace of the outbreak in NSW has seen increasing pressure on the health system. About 1,5000 healthcare workers have been forced to isolate either because they have contracted the virus or are deemed a close contact.
At the same time, the number of people receiving care outside hospital has fallen.
On 14 December there were 3,300 people receiving some form of care out of hospital, about 65% of active cases. By the 22 December that figure had dropped to only 38% of active cases.
According to Basyouny that was both a result of the variant's milder outcomes, but also the ballooning case numbers.
"The system would not cope if we continued to monitor all people who were infected even if they did not have symptoms, so we have to risk stratify people," he said, adding that he had "no doubt" case numbers in NSW would reach 25,000 a day in the coming weeks.
On Friday New South Wales recorded another 5,612 cases of the virus, as indoor mask mandates were reintroduced following a surge in cases of the Omicron variant - it now accounts for about 80% of the state's cases.
Despite reports of the strain's mildness, the rapid increase in Omicron cases has still seen hospitalisation rates rise as many more people catch the virus. In the past 10 days the number of people in hospital with Covid has increased from 168 to 382.
The state's paramedics have also sounded the alarm about record numbers of triple-zero calls, leading to significant delays in response to emergency calls.
The outbreak has also led to increased pressure on the state's testing system, prompting a shift in the government's messaging to urge people not to get tested unless they had symptoms or had been in close contact with a Covid positive person.
"NSW Health reminds people that when you receive that notification from the QR check-in, that just lets you know someone was in that vicinity or premise who subsequently tested Covid positive," Chant said on Friday.
"What we're stressing is that's a prompt, a reminder for you to monitor for symptoms, so please get tested if you're unwell but don't get tested unless you are feeling unwell.
"It is important we keep those testing resources focused on people that have symptoms or people that we've directed from public health to get tested or where you know you've had close contact with a case."
Victoria reported 2,095 new Covid-19 cases and eight deaths on Friday.
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A total of 397 patients are in hospital, including 75 in intensive care, with 40 on ventilation.
The seven-day hospitalisation average is steady at 392.
An indoor mask mandate for people eight years and older came into effect in Victoria on Friday.
Masks will also be required at all major events with more than 30,000 patrons, including the Boxing Day Test at the MCG, but can be removed while seated outdoors.
Masks are already required in retail settings, for hospitality workers and on public transport.
The government is also recommending Victorians work from home over the festive season and hospitality venues are being asked to consider providing seated-only service.
With Australian Associated Press