New Zealand is being urged to heed the lessons from Australia's Covid-19 testing debacle in the event of a similar explosion in Omicron cases in Aotearoa.

Laboratory scientists warn diagnostic testing services would be overwhelmed if people flooded PCR testing sites, but the Ministry of Health insists it is working on a plan to manage demand.

Australian public anger has been growing over the Federal Government's handling of the outbreak, with record high cases, long testing centre queues and a shortage of at-home rapid tests.

Institute of Medical Laboratory Science president Terry Taylor says New Zealand's labs will struggle to cope with unchecked PCR testing rates similar to New South Wales.

"Their labs have been doing upwards of 100,000 PCR tests a day, which we have no question would inundate our own labs and more than likely overrun them."

New Zealand's PCR testing capacity is being expanded to manage around 60,000 swabs per day from February, but that depends on combining samples for testing, which only works when most of the results are negative.

Taylor says the government should devise a national Omicron outbreak plan, prioritising PCR testing for people who were symptomatic.

"I still cannot believe how someone can sit in a car for five or six hours on a hot Sydney day saying they need a PCR test, it really doesn't make much sense.

"There's no need to be sitting in the queue and clogging it up for the people who really need the system."

Some Australian labs have been forced to close temporarily to deal with the backlog in cases.

New Zealand Microbiology Network chair Susan Morpeth says an outbreak of the highly transmissable variant will likely prompt changes to public health advice.

"If an Omicron outbreak starts in New Zealand soon it's likely that we would be overwhelmed by demand for testing," she says.

"The government would need to ask people to only get a swab collected for PCR if they are symptomatic."

Australia's outbreak has resulted in a chronic shortage of rapid antigen test kits, with reports of empty shelves, stockpiling and inflated pricing.

Dr Morpeth says RATs could be used as a diagnostic test if laboratory PCR testing is overwhelmed, but there would need to be clear guidance on when to use them.

"Rapid antigen tests may well be in short supply if we have a huge outbreak in New Zealand," she says.

"I would like to see some clear communication to people about when they should seek a PCR test, when they should use a rapid antigen test and what to do with the results."

The Ministry of Health says it has not done any modelling of Omicron infection numbers, but is working on a testing framework in which RATs are the predominant method for detecting coronavirus infections.

"Using PCR as the predominant diagnostic tool will not be feasible because of the pressure it will place on laboratories and Covid-19 PCR test turnaround times," the ministry says in a statement.

"The Ministry continues to review the ongoing role of RATs as part of its testing strategy in response to emerging variants of Covid-19, such as Omicron, and to alleviate demands on labs for PCR testing."

Almost three million rapid antigen tests are in stock and 20 million on order or in the process of being ordered, the ministry says.

It says it's "working at pace to transition the use of RATs from surveillance to diagnostic" but has not indicated when the tests will be available to the general public at pharmacies and supermarkets.

The Director of Public Health Caroline McElnay says PCR tests are still being relied on here, however, health officials are looking at getting more rapid antigen tests into New Zealand.

The ministry has heeded the advice of Australian officials and is trying to order early.

"Once you start to use them you can actually use up your supply very quickly and I think that's what Australia found themselves in - that they were using their rapid antigen tests at a higher rate than perhaps they'd planned for ...I'm aware that there is a worldwide problem with accessing rapid antigen tests."

Dr McElnay told Morning Report that the priority remained slowing down the arrival of Omicron by focusing on picking up positive cases at the border.

She says the RATs will only be one part of a management strategy of any widespread community outbreak of Omicron.

"We are looking at what has happened overseas and certainly when you have a variant like Omicron prevalent in the community with high rates of disease then those are the situations where rapid antigen tests are very useful."

Dr McElnay says there's some concern about a spread of Omicron cases overwhelming lab testing capacity of PCR tests.

She believes it will take at least a fortnight for Omicron to become widespread and that will provide time to pivot away from the PCR tests, which provided the most reliable results, to the rapid antigen tests.

Pharmacy-supervised rapid antigen tests are free for unvaccinated domestic travellers who meet certain criteria and are also being used by Auckland hospitals and some big businesses.

Pharmacist Clair Connor says there has been a steady stream of people asking about rapid antigen tests at her Auckland chemist.

"On average there are between 10 and 20 people a day just generally asking about rapid antigen testing, wanting to know if they can buy it. They are shocked to find out that they can't," she says.

Connor says some customers have asked if they can ship boxes of RATs to relatives in Australia.

National Party Covid-19 Response spokesperson Chris Bishop says New Zealand has much to learn from Australia's Omicron outbreak.

"I've heard stories of people literally going to 10 or 15 pharmacies before they can find a rapid test. We don't want that to happen in New Zealand. That means we've got to plan ahead," he says.

"We're going to need to use rapid antigen testing on a much bigger scale than we are at the moment."

Bishop says New Zealand should rely on a mix of PCR, saliva and rapid antigen tests, which should be widely available and free or heavily subsidised for certain people.

University of Melbourne epidemiologist Tony Blakely says there is a remote chance New Zealand could shut Omicron out at the border, otherwise the country could "embrace" the variant and manage it well.

"There are some big lessons here for New Zealand and you've got four to six weeks to put them in place," he says.

"Get heaps of rapid antigen tests in before you get Omicron and change your surveillance systems, or at least have them ready to pivot to being less reliant on PCR when the numbers of Omicron go up."

He recommends widespread use of rapid antigen tests, giving booster shots to two thirds of the over-60s population in the next six weeks, mandatory mask-wearing and density limits.

-RNZ/Jean Edwards.