The COVID-19 Response Minister says the government had to weigh up two competing strands of advice, before deciding to make masks mandatory on public transport.
After months of urging from public health experts, masks are now compulsory on all trains, busses and planes around the country, at alert levels 1 and 2.
The rules came into force overnight with some exceptions, such as school busses and for people with certain medical conditions.
Chris Hipkins told Morning Report the government had to consider whether masks were better as a reactionary approach to an outbreak, or a precaution to stop potential outbreaks.
"We're always looking at how we can further reduce risk, things that might not have been justified or that we might not have been fully confident with the basis for doing it a couple of months ago, sometimes those things will change."
Public health officials will be working with bus companies and those operating trains and ferries to make sure the public health advice is reaching them, he said.
"We will take a fairly light-handed approach initially because we want to give people that opportunity to comply."
Cabinet yesterday discussed making QR code scanning mandatory, but the minister said he wasn't confident with where it all shaped up and will seek further advice.
"Compulsion brings a number of issues with it including how do you enforce that, where does the burden lie, does it lie with the individual, does it lie with the business, what do you do with people who don't have phones, who don't use phones regularly. We've got to work through all of those things."
Hipkins said he will be looking at all of the ways to increase the usage of QR codes.
"Vaccines work and that's why we're doing this," Hipkins said.
The ability to move on from the pandemic, he said, rests on the effectiveness of vaccines.
The minister said as of yesterday, about 400 people had been vaccinated. All 12,000 border workers were expected to have their first dose within the first two to three weeks of the campaign kicking off.
"We are getting more vaccines coming through, so Pfizer have indicated that they'll be shipping to us smaller batches regularly."
It would be highly unlikely that someone would test positive for COVID-19 straight after having the vaccine, he said.
"The COVID testing will still help us indicate whether somebody who's been vaccinated may have picked up COVID-19 say from someone who's coming back into the country. But the likelihood of them developing sufficient viral load, pass that on to someone else reduces significantly."
Hipkins said he wasn't told of any additional community cases overnight but it's unlikely that any new cases wouldn't be connected to the current cases.
Papatoetoe High School students and staff considered close contacts of the current cases won't be back at the school until completing 14 days of isolation.
"They will have to have two tests, if we were to see any further spread it would be in that group first."
Hipkins said we can start to feel more confident there won't be further spread of the virus as we head towards the end of the 14 day incubation period of the current cases.
But, he added, "It's still a virus, you never say never."