New South Wales has recorded Australia’s highest ever daily Covid case tally as the Omicron variant, combined with a wave of Delta cases spread at Christmas gatherings, has caused the number of infections to spike.
The spike comes just days after the NSW government decided to go ahead with removing almost all remaining Covid restrictions, including the requirement to wear masks in crowded retail settings.
It is an approach that has baffled some epidemiologists, who say it is too early to base public health decisions on the assumption that the Omicron variant will be more mild than previous strains.
“Everybody is banking on [Omicron] being mild but it would have to be extremely mild for it to not be a problem given the significant increase in cases,” said Prof Nancy Baxter, the head of the school of population and global health at the University of Melbourne.
NSW recorded 2,482 cases on Saturday, more than quadrupling its daily case tally in just five days, resulting in a spike in cases that is steeper and taller than recorded during the Delta outbreak in the middle of the year, when Sydney was put into lockdown for more than three months. There are currently 206 people in hospital, and one person died overnight.
In the five days between Sunday and Friday, the reproduction number in NSW – which represents how many people the average positive case will infect – increased from 1.37 to 2.12, meaning case numbers could double every four days.
Victoria recorded 1,504 new cases on Saturday, none of which were reported to be the Omicron variant. Seven people died and the number of people in hospital increased to 384.
South Australia recorded 73 new coronavirus infections amid a growing outbreak, posting record numbers for the second consecutive day. It brought the total number of active Omicron cases in the state to eight.
Twenty-nine cases were locally acquired in South Australia and have been linked to a positive case, and four more acquired the infection locally but were unlinked. Two more were linked to infections interstate and 37 acquired the infection somewhere in Australia, with no known source. One was a person who acquired the infection overseas.
Tasmania also reported one new case of Covid-19, bringing the total number of active cases in the island state to four, four days after the state reopened to visitors.
The NSW department of health on Saturday said it would no longer undertake genomic sequencing for all potential cases of Omicron, only those where it may make a difference in treatment.
With the high number of COVID-19 cases now in NSW, NSW Health will only undertake genomic sequencing for the Omicron variant in the circumstances where it will make a clinical difference to the care of a patient.
— NSW Health (@NSWHealth) December 18, 2021
There are early signs that monoclonal antibody treatments, which are used against other variants of the coronavirus, may not be as effective against Omicron.
There have been 226 cases of the Omicron variant recorded in NSW to date.
Baxter said it was sensible, if resources were stretched, to reserve the genomic sequencing capability for those cases where it may affect the treatment options. In two weeks, she said, it may not matter at all – Omicron will be the dominant variant.
On Wednesday, the NSW government went ahead with a plan to scrap mask mandates in some indoor settings such as supermarkets and cinemas, and dropped QR check-in codes for all except high risk venues like gyms, aged and disability care facilities, hospitals, pubs and clubs, and large outdoor music festivals. Density limits were also dropped.
The Victorian government also eased some restrictions, particularly around the requirement to show proof of vaccination status, but the planned easing of mask rules did not take place because of the risk posed by the Omicron variant.
The Australian prime minister, Scott Morrison, said on Saturday that the national plan was “not about case numbers”.
“What matters is hospitalisations, ICU, people on ventilators, and severe illness,” he said. “We have been planning for this. We planned to live with the virus. We didn’t plan to remain shut in.”
Baxter said it appeared that many Australian governments had decided to “hope for the best and plan for the best” despite the lack of data around the impact of Omicron on hospitalisations and long Covid.
“You can hope for the best, I don’t have a problem with people hoping for the best, she said. “But planning for the best is not generally what you do in a pandemic, because if you’re wrong …”
Australia may be at particular risk from Omicron, she said, because the AstraZeneca vaccine does not appear to be effective against transmission of this variant. There is very little data on whether it is effective against severe illness or hospitalisation. AstraZeneca was widely used in Australia, particularly among older Australians.
The Australian Technical Advisory Group on Immunisation has reduced the interval for booster shots – of either Pfizer or Moderna mRNA vaccines – from six months to five, and Guardian Australia revealed on Friday that NSW was considering reducing that interval to four months given that many people in that state received the AstraZeneca vaccine, often on a condensed timeline.
“I had a double AZ and I am nearly four months along going into the holidays,” Baxter said. “I feel completely unprotected.”
Baxter said that early indications the Omicron variant was more mild than the Delta variant were tempered by the fact that it appears to be much more infectious. Because even if fewer people are seriously ill or hospitalised, the case load could still, with higher infectivity, be enough to put significant pressure on the health system.
“You can’t turn your back when the tsunami is coming, you can’t say ‘I don’t care about the tsunami’,” she said.
“[Government] had a plan and they are sticking to the plan, but Omicron does not care about your plan. Covid does not care about your plan. What Australia is doing is completely contrary to what everyone else is doing.”
At the very least, Baxter said, governments should be requiring people to wear masks indoors. She also said the cloth masks that became ubiquitous in 2020 may not protect against Omicron, and recommended people wear a well-fitted P2 mask.
“A cloth mask will protect other people from you if you have Covid – you need to protect yourself from other people,” she said.
“Masks do not stop you from doing anything. Unless we are a country of babies, unless we are a country of total whiny babies, we can still wear masks.”
This article was amended on 19 December 2021. An earlier version stated masks were no longer mandatory on public transport, at airports or for unvaccinated hospitality staff in NSW when they are still required in those circumstances.