Covid cases are continuing to surge, doubling in New South Wales and Victoria in just a fortnight.
Hospitalisations and deaths have also risen sharply, prompting health experts to suggest a limited return to mask-wearing to curb the rise in cases.
NSW and Victoria recorded a combined 48,267 new infections on Friday, up from 22,676 two weeks ago.
In its latest reporting period until 18 November, NSW Health reported 27,869 new cases up from 12,440 on 4 November.
In Victoria, the story was similar, with 20,398 new cases reported on 18 November, compared to 10,226 cases two weeks ago.
Hospitalisations were also beginning to reflect the increase in cases.
Hospitalisations in Victoria jumped by 28.5% compared with a week ago, sitting at a seven-day rolling average of 352 admissions. There were 46 deaths recorded and eight people in ICU.
In NSW, there were 1,148 people admitted to hospital, with 39 deaths and 37 people in ICU.
Emergency department presentations also shot up from 169 to 248.
NSW Health said there were several emerging subvariants of the virus circulating, including Omicron strains BA.2.75 and BQ.1 sub-lineages.
It recommended a return to mask-wearing indoors in places unsafe to physically distance and on public transport to limit the spread of the virus.
“The current wave of Covid-19 cases continues to grow,” it said in its latest surveillance report, while acknowledging testing rates had significantly dropped.
“On 14 October the mandatory reporting of positive rapid antigen tests in NSW was removed,” NSW Health said.
“PCR testing rates have almost halved from what they were at the beginning of the Omicron BA.4/5 wave … the changes in Covid-19 testing and reporting means that notification numbers no longer reflect the level of community transmission.”
While it had become difficult to measure accurate levels of Covid-19 in the community, the proportion of positive PCR tests had also jumped from 14% to 16% in NSW, while testing increased by 17.7% on the previous week.
The state’s sewage surveillance program, which tests for fragments of Sars-CoV-2 – the virus that causes Covid – tested positive across all catchments.
Similarly, all catchments tested in Victoria recorded a “strong” or “very strong” detection of the presence of Covid-19.
The federal health minister, Mark Butler, told 3AW he expected the new wave of the virus to continue to rise, but hoped it would peak by Christmas.
“I don’t think there’s any question case numbers and hospitalisations are going to increase for a little while,” he said.
“The advice I’m getting is this is likely to follow the trajectory of Singapore … and their wave in the words of the technical advisers we receive advice from was ‘short and sharp’ and it’s come down very quickly.”
The chief medical officer, Prof Paul Kelly, said the new Covid wave was largely being driven by community transmission of Omicron variants XBB and BQ.1.
“While evidence is still emerging, the experience to date with these two variants overseas is that they do not appear to pose a greater risk of severe illness and death – and that the Covid-19 vaccines provide good protection against these outcomes,” he said.
“The overseas experience is that these new variants have driven increases in case numbers – and hospitalisations at a rate proportionate to these increases – because of their ability to evade the immunity provided by prior infection and vaccination.
“It’s therefore timely to focus on the actions we can all take to reduce the threat of these new variants, keep the pressure off our health care workers and hospitals and continue to look forward to our summer plans.”