Households should add masks to their emergency supply kits in the case of further Covid-19 outbreak, Health Minister Chris Hipkins says.
The masks do not need to be medical-grade and can be reusable ones that can be bought in stores, online or made.
"We're the envy of much of the world and we enjoy freedoms that so many others don't. But it isn't scaremongering to say that could all change and it could all change very quickly.
"That is a statement of fact," said Hipkins.
"We simply cannot afford to be complacent. Our best chance of preserving the gains that we have all made, of keeping the freedoms that we all now enjoy is to stay ever-vigilant."
The updated guidance on masks comes as New Zealand recorded no new Covid cases in the past 24 hours with 97 days since the last evidence of community transmission.
Hipkins said if New Zealand were to ever return to alert level 2, Kiwis would be encouraged to wear masks in situations where they can't physically distance - like on public transport.
There are 23 active cases in border hotels.
There is advice on the Ministry of Health website about how to put on a mask, including a demonstration by director general of health Ashley Bloomfield.
"This is about general preparedness - it's about being ready, it's not cause for alarm," he said.
Yesterday, National MP Gerry Brownlee issued a press release saying the Government "needs to come clean on what they know about the state of Covid-19 in New Zealand".
Brownlee said it didn't stack up that they were warning about a second wave when there were so few cases.
"What do these guys know that they are not telling us?"
Hipkins said he "utterly" rejected they weren't being honest about community transmission.
"I would encourage Gerry Brownlee to swap the tinfoil hat for a face mask."
Hipkins also announced it would be trialling the CovidCard technology - which is actually a dongle on a lanyard - in Rotorua.
About 250-300 people would be involved in the trial which is being run by the University of Otago.
It would give researchers insight into how it would work in the real world, including whether people actually wear it, Hipkins said.
It will not track people, but keep a record of which other CovidCards was in the vicinity of.
But the mainstay of the contact tracing was the manual system, Hipkins said, and he called the CovidCard another "tool in the toolbox", alongside the Covid Tracer app.
Hipkins continued to encourage use of the app and urged businesses which had taken down their QR codes to put them back on prominent display.
The cards could be deployed later this year, but ministers say at this point they're not anticipating making them mandatory.
Hipkins and Bloomfield also announced a slew of pop-up testing sites which would be rolled out around the country as part of the community surveillance plan.
Anyone will be able to be tested - they don't have to have symptoms.
There are sites in Auckland in Northcote, Henderson, Grafton, Wiri and a yet-to-be determined suburb in South Auckland.
As well there will be sites in Milford Sound, Christchurch and two in Palmerston North and another in New Plymouth.
"Please make use of these pop-up centres - getting a test helps us rule out cases of Covid-19 in our communities, and you are helping keep your families and your team of five million safe by getting a swab," Bloomfield said.
And after weeks of the Government asking people to get tested, for the first time in more than a month more than 5000 tests were processed yesterday.
Bloomfield said it was encouraging to see the rise in testing numbers and repeated how important it was for people to get tested if needed.
Hipkins said he was "very heartened" by the current testing numbers and he was "much more comfortable".
But there was still more work to be done in testing at the border, he said.
Anyone working at the border can be tested and there is a pop-up testing site at Auckland Airport this week.
An earlier trial conducted in May by the University of Otago in conjunction with the Nelson Marlborough DHB found the CovidCard worked under controlled conditions "so we believe there is merit in exploring it further".
"This research will allow us to understand how the cards would work in a real-world scenario, whether they are compatible with our contact tracing systems, and whether the public would accept and use the cards if they were rolled out," Faafoi said.
Rotorua community leaders and iwi have been consulted, he said.
Hipkins said initial assessments highlighted that the CovidCard could make "a real contribution" to New Zealand's contact tracing processes.
"While manual processes remain the critical component for contact tracing, we know digital solutions can help make contact tracing faster and more effective. This is important from a public health perspective and also in supporting our economic and social recovery," Hipkins said.
"It's fair to say that no single technology to 'solve' contact tracing has been identified anywhere in the world. That's why we need to explore all available technology options.
"We are continuing to improve the NZ Covid Tracer app, which includes looking at how technologies like Bluetooth can be utilised to further support contact tracing and have also been investigating the proposed CovidCard."
Key considerations will include whether the CovidCard meets high security and privacy standards and can be used by a wide range of New Zealanders, Hipkins said.
He said the CovidCard technology was another tool in the toolbox for contact tracing system as digital solutions can make it quicker.
Hipkins said it was vital to stay "ever vigilant" about Covid-19 as the virus wouldn't be taking six weeks off for the election.