Experts have called for New Zealand to urgently test itself against simulated community outbreaks of Covid-19 – and even run regional-level "mask days" – to better prepare the country against a Melbourne-like disaster.

It comes after Director General of Health Dr Ashley Bloomfield this morning warned community transmission in New Zealand was inevitable, and that masks could become mandatory if the country was pushed back into level 3.

Bloomfield said contact tracing capability was in good shape, with a large-scale test run planned in a few weeks' time, while testing capacity was now above 3000 cases each day.

Experts who spoke to the Herald today saw a critical need to hold drills that assumed infectious cases had got into the community, amid warnings they might not be discovered until there had been several different generations of the virus.


They also backed the idea of regional exercises where people were required to wear masks on a given day within indoor areas and crowded settings like public transport.

Health Minister Chris Hipkins today told the Herald there was "considerable ongoing work" on preparations for any future community cases.

"Simulated scenario events are obviously an option, but are not something we would announce in advance - you don't get advance notice of outbreaks after all," he said.

"I expect to have more to say about the issue of masks in coming days."

Melbourne is seeing a fresh, deadly wave of Covid-19, prompting the State of Victoria to declare a state of disaster, with strict lockdown rules and mandatory mask-wearing across the state.

While it's been more than three months since the last case of Covid-19 was contracted in New Zealand – all cases in the past 95 days have been detected and contained at the border – the Government has just re-launched an awareness campaign urging people to "be ready" and get tested if needed.

In reporting two fresh cases today, the Ministry of Health warned that "every New Zealander needs to be prepared for the virus to re-emerge".

Otago University epidemiologist Professor Michael Baker said there was a sense of complacency – "even smugness" – in New Zealand that Covid-19 wouldn't return to our communities, while it raged around the world.


"But New Zealand is not sealing itself off at any point from the outside world – and if you go down the list there are multiple points [where the virus could enter]".

That included people and workers in managed facilities, where there were currently 22 active cases, along with airport staff, and those aboard vessels and workers who serviced arriving ships.

People line up to enter a supermarket hours before a citywide curfew was introduced in Melbourne this week. Photo / AP
People line up to enter a supermarket hours before a citywide curfew was introduced in Melbourne this week. Photo / AP

"Right now we have a 'low probability, high consequence' situation, which is one of the classic problems of risk management," he said.

"It means, the longer we go with a low-probability situation, the higher the chance is that we'll get a breach.

"And while we know that, of the roughly 6000 people in facilities at the moment, less than half a per cent will be infected, we need to consider the sheer numbers over time, and the reasonable likelihood that something will go wrong.

"If there was suddenly an outbreak in South Auckland tomorrow, for instance, it could take several generations before people were even aware of it. Small numbers of people can go on to infect large numbers of people."


University of Canterbury mathematician Professor Michael Plank said Victoria's current surge – 384 of its 4775 active cases were reported in the last 24 hours – could easily play out in New Zealand.

New Zealand's effective elimination of the virus had pushed its basic reproductive number – or R0 value – below one, but in our present level 1 environment, that could shoot up quickly.

"We are in the nice position of not having any data, but [the R0 value] would be significantly greater than one at the moment."

Plank likened New Zealand's present uninfected and free-moving population to a "big pile of kindling, just waiting to go".

"Good borders are the first line of defence, and contact tracing is the second, but I think we've got a bit of work to do in terms or readiness with contact tracing, and people keeping a record of where they've been."

The Government has redoubled efforts to get Kiwis using the NZ Covid Tracer App, with shops, restaurants and schools being encouraged to display QR codes.


While 83,337 posters have been created, and 1,885,632 poster scans and 39,730 manual entries into the app, just 630,700 people have registered.

"Right now we have a 'low probability, high consequence' situation, which is one of the classic problems of risk management," Otago University's Professor Michael Baker says. Photo / Supplied

"We can't afford for people to wait until there is a case of community transmission to start using the app – we need to quickly be able to isolate any contacts of a future case in our community before the virus spreads out of control," Bloomfield said.

"By keeping a record of your movements, you will be able to quickly call upon your digital or written diary of your movements to assess whether you may have been exposed to a case of Covid-19.

"Now is the time for New Zealanders to get the app and get in the habit of using it – it is simple, quick and now has extra functionality allowing for manual entries to record where you have been."

University of Auckland scientist Professor Shaun Hendy urged people to keep records of where they'd been so they could be traced faster, and to ask to get tested if they felt they had symptoms.

"With relatively low numbers of testing, we could potentially have a large number of secondary and tertiary cases before we actually realised what was going on," he said.


"It's winter at the moment, the virus does do a bit better in colder weather, so the risks are pretty high if someone picked up an infection and spread it into the community."

Baker felt everyone in New Zealand should have a fabric mask they could use if needed, and said he'd like to see national or regional "mask days" to prepare for outbreak.

"In Victoria, there has been quite a delay here. And you can't go from having no experience with masks at a population level to being able to use them," he said.

Director general of health Dr Ashley Bloomfield said the Government was actively looking at scenarios where mass masking may be required. Photo / Mark Mitchell
Director general of health Dr Ashley Bloomfield said the Government was actively looking at scenarios where mass masking may be required. Photo / Mark Mitchell

"And even if you've got stocks of them, you've got to get them to people and they have to know how to use them."

Baker saw more value in everyone having their own re-useable fabric mask, rather than the more expensive option of providing disposable ones.

Bloomfield told Morning Report today the ministry was actively looking at scenarios where mass masking may be required.


"We're looking at situations where masks might be deployed and recommended for the general population ... our thinking at the moment is that even at alert level 2 we would be encouraging people to use them in confined spaces, so public transport, shops and so on."

But that would be considered voluntary at level 2, he said, and his intuition is that it would be ramped up to mandatory at level 3.

"Because remember you're deploying all these things including the masks to try and avoid going into a lockdown again."

While there was no firm decisions on masks yet, he encouraged people to have some stocked at their homes, in the same way they have an earthquake kit in case of emergencies.

Work was also underway to check how much is available in the private sector and to ensure there was enough for everybody, he said.

That marked a notable change from the Government's earlier stance - on the back of an official review of studies - that there wasn't enough evidence to either support or discourage mask use.


Bloomfield told Newstalk ZB the Government was generally going "full steam ahead" on planning and preparations.

"We've got everything in place we think minimises the risk down to as low as possible but there are still hundreds of people still working in the facilities and working at the border," he said.

"So far we have been successful but remember that is where the cases came from in Victoria which has led to this huge outbreak.

"This is a tricky virus and we just have to be very vigilant. Part of that is doing testing in the community to detect any infection that might get through as quickly as possible."

The fresh warnings sounded today stood in stark contrast to comments by former prime mInister Sir John Key, who said New Zealand's economic hit could be eased by softening border restrictions.

- Additional reporting: RNZ