Hospitals should consider preparing for a worst-case scenario of more than 1500 cases per day in hospital, say a group of public health experts who have assessed Omicron waves across the Tasman.
Otago University's Dr Jennifer Summers and professors Nick Wilson and Michael Baker are recommending a raft of measures to prepare for a major outbreak, such as rolling out vaccines, masks and rapid antigen tests, boosting hospital capacity, and arranging care for the elderly and at-risk.
"If New Zealand follows a similar path to Australia, we can expect to see high hospitalisation numbers along with ICU numbers reaching or exceeding capacity," the three researchers wrote in a new analysis.
"However, if more extensive public health measures are promoted by the Government and adopted by New Zealanders, the impact on public health and the health care system can be reduced."
The arrival of Omicron in Australia drove a new wave of infections over summer, peaking at January 19 with around 5302 people in hospital, and 424 in intensive care units.
If those numbers were applied to New Zealand on a per capita basis, we could expect a peak of 1107 people in hospitals and 90 in ICU.
While numbers would likely be lower, the researchers said the country should consider "preparing for a worst-case scenario of over 1500 cases per day in hospital".
They pointed out Omicron had pushed confirmed Australian Covid-19 cases – mainly in hard-hit New South Wales and Victoria – to more than 2.3 million over the past two months.
That was "substantially higher" than the 215,046 total cases recorded there between January 2020 and November last year, when the first Omicron cases were detected.
"Furthermore, Australia just experienced its highest daily death toll with 98 individuals dying from Covid-19 on January 28, 2022."
That swell in cases drove a sharp increase in hospital and ICU admissions, which were notably higher than rates observed when Delta was biting New South Wales and Victoria hardest over September and October last year.
"This surge has led to extreme stress on the health system, although it appears that the Omicron wave may have now peaked in New South Wales and Victoria."
In mid-January, New South Wales alone saw peaks of 2863 hospital cases and 217 ICU cases – which respectively equated to 1792 and 136 here on a per-capita basis.
Going by per 100,000 of population, Australia's highest hospitalisation peak was observed in Northern Territory – reaching 49.1 per 100,000, or an equivalent per capita peak of 2518 hospitalisations here.
Looking at Australia's national numbers – and considering hospital and ICU surges across the country may yet not have reached their highest level – the researchers came to their overall peak equivalents of 1107 hospital and 90 cases in a day in New Zealand.
While we could draw many lessons from the Australian experience, they nonetheless said comparisons needed to be treated with caution.
That was namely because of key differences like population demographics, public health measures, vaccination levels, health system capacity and the fact states were grappling with major Delta outbreaks when Omicron hit.
Nevertheless, they said more weight could likely be put on a straight comparison with Australia than estimates drawn from the University of Washington-based Institute for Health Metrics and Evaluation (IHME).
Under its latest "mostly likely" scenario for New Zealand, the IHME data predicted that 2395 hospital beds would be needed by March – including around 458 in intensive care units - not long after daily cases involving some level of sickness had grown to around 11,000.
Yet ICU capacity was still a big concern, they said.
A recent leaked report revealed there were just over 100 intensive care unit (ICU) beds available across district health boards, as at late last year.
While the Government has since insisted that capacity could be surged to up to 550 ICU beds, clinicians have suggested a more realistic figure might be closer to 350.
Looking at differences in vaccination rates, they found about 76 per cent of Australia's total population had received at least one dose, 74 per cent were double-jabbed, and about 22 per cent had received a booster.
As of this week, those same rates here were 83 per cent one dose, 77 per cent two, and 27 per cent boosted.
"These differences in vaccination levels mean that New Zealand is ahead of Australia in primary vaccination and booster coverage at the start of our expected Omicron wave," the researchers said.
"However, issues of equity with the vaccination roll-out are observed in New Zealand as vaccination rates for Māori and Pasifika are lower than European/Other and Asian populations, which may leave some ethnic groups at greater risk for poorer outcomes in the upcoming Covid-19 wave."
Among the priorities they listed for New Zealand now were continuing to lift vaccine coverage for vulnerable populations, slashing the dose interval for five to 11-year-olds, and considering booster access for teens.
The Government should encourage "widespread" use of masks for the public – ideally high-quality respirator masks like N95s – with a particular focus on groups like the elderly.
As well, masks and rapid antigen tests could be supplied to specific sectors of the workforce, such as all hospital, primary care and aged-care residential workers, education staff, and essential service workers.
Preparations should also be made to ensure the elderly and at-risk had access to services and supplies over the next few weeks to months.
And new work to address poor ventilation in schools, universities and early childhood centres should be extended to all health care and essential service settings, they said.
University of Melbourne-based Kiwi epidemiologist Professor Tony Blakely told the Herald said New Zealand could anticipate half the population to become infected with Omicron.
Like his Otago counterparts, he stressed the need to protect the elderly and those with co-morbidities.
"That means them hunkering down, and families dropping the shopping off while the infection runs on through."
Keeping Omicron out of aged care facilities was much harder, he said, but rest homes could minimise the risk by ensuring staff were boosted and wearing high-grade masks - and even isolating residents in their rooms if needed.
"We've now had around 600 deaths in aged care here within the last two months, which shows you where a lot of the mortality is concentrated."
Generally, he said the key was to quash the peak of the Omicron wave as much as possible.
"This is all about flattening the curve now – and not freaking out."