“We need to act now, or risk the virus taking hold as it has elsewhere.
“We currently have 102 cases, but so did Italy once.”
Ardern’s announcement came as New Zealand confirmed a jump of 36 positive tests for the virus in the past 24 hours, including the first two cases of community transmission.
New Zealand has recorded 102 cases, and no deaths, of COVID-19.
By comparison, Australia has recorded at least 1600 cases.
The measures, championed by public health experts and supported by all of New Zealand’s political parties, will allow New Zealanders outside to walk the dog, or exercise, or to visit supermarkets or health services.
But only industries deemed “essential” – including health and emergency services workers, police, some public servants and media – will be allowed to continue, and otherwise citizens will be asked to stay home.
Ardern said fresh advice and modelling in the case of widespread transmission made the lockdown essential.
“If community transmission takes off in New Zealand the number of cases will double every five days,” she said.
“If that happens unchecked, our health system will be inundated, and tens of thousands of New Zealanders will die.
Ardern said she was fully aware of the sacrifices she was asking from Kiwis.
“I do not underestimate what I’m asking New Zealanders to do. It is huge. And I know it will feel daunting,” she said.
“Everything you will all give up for the next few weeks, all of the lost contact with others.
All of the isolation and difficult time entertaining children, it will literally save lives, thousands of lives.
“The worst case scenario is simply intolerable. It would represent the greatest loss of New Zealanders lives and our history. And I will not take that chance.”
Parliament will also be recalled for an emergency session on Wednesday, in which Ardern will table an epidemic notice to enforce the lockdown.
It remains to be seen whether the New Zealand election can be held on September 19 as planned.
Also on Monday, New Zealand announced a program of quantitative easing to help its coronavirus-struck economy, the Reserve Bank (RBNZ) saying it would begin a government bonds buying program, capped at $NZ30 billion ($29.5 billion) over the next 12 months.
“The program aims to provide further support to the economy, build confidence, and keep interest rates on government bonds low,” a RBNZ statement read.
The central bank will buy bonds owned by investors equivalent of up to a 10th of New Zealand’s annual GDP.
In doing so, the RBNZ frees up cash for those investors – including retail banks – to spend in other areas, with a flow-on effect that should see those retail banks lower their personal and business lending rates.
The action comes after the reduction of New Zealand’s official cash rate to just 0.25 per cent, the lowest in its history, and has full government support.
Finance Minister Grant Robertson signed a memorandum of understanding and letter of indemnity with the Reserve Bank to green-light the bonds buying.
“This is part of our strategy to mobilise all arms of New Zealand’s economic infrastructure in our fight against the COVID-19 virus,” Robertson said.
“We are all uniting together – the government, the Reserve Bank, private businesses and the retail banks – to cushion the impact on New Zealand from this global pandemic.”
On Monday, New Zealand shares plunged dramatically, with the NZX 50 Index dropping 10 per cent.
Robertson also announced a top-up to the government’s a $NZ12.1 billion economic stimulus package announced last Tuesday.
A cap has been removed on handouts to businesses designed to help employers retain staff through the economic crisis.
That means the government is borrowing cash to give to employers to give to staff, ensuring half of the country’s workforce stays in work.
It will cost approximately $NZ9.3 billion, up from the previously budgeted $NZ5.1 billion, over the next three months.