Bloomfield said the definition of "coronavirus elimination" was getting down to a small number of cases that can be stamped out with rapid identification, isolation and contact-tracing.
The Prime Minister has hit back at the suggestion the Government could have been putting every person returning to New Zealand into quarantine since the lockdown began two weeks ago.
Jacinda Ardern today announced a blanket quarantine of New Zealanders returning from overseas.
From midnight tonight every Kiwi boarding aflight to return home will be required to undergo quarantine or managed isolation in an approved facility for a minimum of 14 days.
However when questioned about why it hadn't been done earlier, Ardern said it was not as simple as it sounded.
"It is not a matter of just everyone who is coming through, whopping them into a hotel," she told Newstalk ZB's Heather du Plessis Allan.
"We've got to make sure we've got the proper public health people available. We've got to make sure that we're using facilities where people keep enough distance - even when they are exiting their rooms so people can still go out and get fresh air.
"We've got to put in place all of the services for food, mental health care needs, public health."
It took a bit to scale it up "but now we are ready to do it properly for every single person on top of the 1000 we've already done."
"There was a point at which we actually just could not have done it because we just didn't have the capacity. We've built that capacity and we've built it safely."
The Government did not want to create a "Diamond Princess" facility - in which Covid 19 could be passed on easily in confined spaces, like the cruise ship that was tied up in Japan for many weeks.
Jacinda Ardern today announced a blanket quarantine of New Zealanders returning from overseas. Photo / Getty
"If we don't have enough separation in people's ability to move through the facility without being in contact with each other, we risk contagion and spread."
Suitable hotels had been identified that could be used safely, and that excluded motels and backpackers.
"It is not a simple matter of every single person coming in and jumping on a shuttle bus and being taken to the Sudima. It is much more complex than that. We have moved as quickly as we could to have now a system where not one person who arrives at the border will be going home."
Under the new restrictions, every New Zealander returning from overseas will go into quarantine for a minimum of 14 days.
Those with symptoms will be in quarantine and will not be allowed to leave the hotel room, but those in managed isolation will be able to get some fresh air.
"No-one goes home, everyone goes into a managed facility," Ardern said.
Passengers with symptoms will be put in quarantine and will not be allowed to leave the hotel room. Photo / File
She said there was no end point for the border controls, as borders will continue to be a high risk of importing a Covid-19 case.
"Even one person slipping through the cracks and bringing the virus in can see an explosion in cases, as we have observed with some of our bigger clusters," Ardern said.
"A network of up to 18 hotels will be used to implement this approach, of which one to two will be specifically set aside for those under strict quarantine conditions."
Campervans will also be used for quarantine, should they be needed.
Police will monitor the facilities and the military could also be used for quarantine enforcement.
