Australia’s fourth Covid wave is likely to peak before Christmas as the rate of hospitalisations and infections begin to slow.
Cases have continued to increase nationwide for the sixth consecutive week, however at a slower rate. This suggests a plateau in cases would arrive by the first week of December, in line with pandemic modelling, if it has not already.
New South Wales recorded 31,531 new Covid cases in the weekly reporting period, a 13% increase from last week’s 27,869.
Victoria recorded 22,281 new cases in the latest weekly reporting period, a 9% increase on the previous week’s 20,398.
Previously, cases in NSW and Victoria were doubling in just a fortnight, driven by a “soup” of Omicron subvariants.
Emergency department presentations, however, had risen to 314 from 262 in the last reporting period.
James Wood, an associate professor of epidemiological modelling of infectious diseases at the University of New South Wales Sydney, said cases were “very close” to the peak in NSW, if it had not already occurred.
“I suspect they will remain around current level for the next week or two and then decline,” he said.
“I definitely expect cases to be markedly lower by Christmas. It looks like the new Omicron subvariants are already pretty close to dominant and that rising immunity from infections and reduced transmission as we move into summer will be what pushes cases down.”
In Victoria, there were 68 deaths recorded in the past seven days – up from the 46 in the previous week. Health authorities said deaths may not have occurred in the week they were formally reported.
Hospitalisations increased by 22% to an average of 430 a day, and there were 15 daily ICU admissions, almost double the previous week’s 8.
Victoria’s chief health officer, Brett Sutton, said hospitalisations and case numbers were expected to increase for several weeks with a likely peak forecast around early December.
“Indications from Singapore and western Europe suggest this wave may pass relatively quickly, although differing local conditions may have an impact,” Sutton said.
The state’s latest wastewater testing results found a strong detection of Sars-CoV-2 – the virus that causes Covid – in every geographical area, and a “very strong” detection in Craigieburn and Portland.
Similarly, all tested samples in NSW contained fragments of Sars-CoV-2, with a particular increase in Quakers Hill in western Sydney.
Queensland recorded 10,082 new cases in the latest reporting period and 14 deaths, a decrease on the 10,106 cases and 15 deaths reported the previous week.
Hospitalisations, however, had increased by 27%. There were 312 people being treated in hospital with Covid and eight in ICU, compared with 245 admissions and five in intensive care the previous week.
Catherine Bennett, chair in epidemiology at Deakin University said it was clear cases were “starting to taper” nationwide and had already flattened out in Tasmania, Queensland, Western Australia and South Australia.
“I’d describe it as a plateau than a sharp peak,” she said. “The coming down is less certain, we’re still learning about a mix of viruses and you’re still at 50% higher likelihood of acquiring the virus compared to the start of the month.
“But hopefully it’s at the highest it’ll be and it’ll be a more normal Christmas this year.”
The latest wave was now made up of a mix of Omicron sub-lineages, including BR.2 and BQ.1.1.
There were 11 separate variants of Covid-19 circulating in NSW, including three “recombinant” variants. A new BA.2.75/BA.5 recombinant, XBF, made up more than 10% of sequenced cases in Victoria.
Bennett said the Covid variants were currently reproducing at a rate of 1.1, “barely a replacement” due to hybrid immunity, recent infection and vaccination rates.
She said the relatively low number of hospitalisations and ICU admissions to the virus compared with previous waves was also cause for optimism.
“Early predictions were the outbreak would behave in a similar way to waves overseas, and that looks to be the case,” she said.
“If we don’t see hospitalisations rise and an impact on the daily death rate that’s most important thing … and aged care outbreaks will be one to watch.”
A spokesperson from the federal health department said cases had increased by 11% nationwide in the week ending 22 November, while hospitalisations rose by 14%.
They said while there was usually a lag in hospitalisations which may increase after case numbers declined, numbers remained “well below” the earlier winter peak.