• Four-stage alert system for Covid-19 announced
• New Zealand moved up to Covid-19 alert level 2 – reduce contact
• New Zealanders over 70 and those with certain medical conditions told to stay at home as much as they can to reduce risk of contact with the virus. There are 528,000 people aged 70-plus in New Zealand
• Workplaces to implement plans to reduce person-to-person contact, including work from home where possible
• Limit all non-essential domestic travel
• Covid19.govt.nz: The Government's official Covid-19 advisory website
Prime Minister Jacinda Ardern is asking all people over 70 or with compromised immune systems to stay at home and all non-essential domestic travel to be curtailed.
And she had a stern message for New Zealanders who are not taking the threat of Covid-19 seriously, saying they should think about their friends and family and consider that their blithe approach could imperil people's lives.
In her first ever address to the nation today, she also introduced a four-tier alert system based on the spread of the virus. New Zealand is currently at level two.
Level two means the disease is contained but the risks are growing, and contact with other people should be reduced through cancelled events, increased border measures, and people working from home.
Public health officials are currently investigating two confirmed cases - one in Auckland and one in the Wairarapa - that could have come through community transmission, and Ardern said the alert system could be changed quickly to put those regions into lockdown - if necessary.
"We are constantly monitoring these settings," Ardern said.
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There are 528,000 people aged 70-plus in New Zealand, including Deputy Prime Minister Winston Peters, who is 74.
Ardern said in a press conference after her address that Peters would continue to come to work as he was an essential part of the Government's Covid-19 team, but he would exercise good health practices such as physical distancing and handwashing.
Neighbours, family and friends should be willing to bring supplies to the homes of over-70s or those with compromised immune systems, and if they needed to leave home, they should practice physical distancing.
Ardern said people should be "very practical" about travelling domestically and should ask themselves if their travel was essential.
"Every unnecessary movement gives Covid-19 a chance to spread," Ardern said.
During her address, Ardern said closing the borders seemed "unimaginable" a month ago, but now seemed to be an obvious step to help combat the outbreak.
She warned against misinformation, and implored people to look at the Covid19.govt.nz website to see the Government's official information.
"Please do stay tuned, and we will share daily updates.
"I ask that New Zealand does what we do so well. We are a country that is creative and community-minded.
"We know how to rally. We know how to look after one another.
"Be strong, be kind, and unite against Covid-19."
Thirteen new cases in the last 24 hours
New Zealand now has 52 confirmed cases of Covid-19, including the two cases which have no link to overseas travel.
"At this point, we cannot rule out a risk of community transmission in these [two] cases," Director General of Health Ashley Bloomfield told a press conference this morning.
"We always knew that cases not linked to travel could happen and we are prepared for that," he said.
A further 13 positive tests were confirmed in the past 24 hours, the biggest jump in cases in a single day so far.
In a press conference with Bloomfield after her address to the nation, Ardern said Covid-19 would be in New Zealand for some time, and the new restrictions would likely be the new norm for months.
Parliament would also have to adjust to the new norm, and guidelines were being drawn up about MPs' travel and work to keep the spread of Covid-19 to a minimum.
"The Government will not be travelling overseas," Ardern added.
The risk of community transmission was growing, she said, but there was still no need to close schools unless there was a positive case in one.
Restaurants and bars were working with the Ministry of Health about how they could still do business while adhering to the ban on gatherings of 500 people outdoors and 100 people indoors.
The goal is to slow down a "tidal wave" of Covid-19 and break it into smaller waves, which would reduce the impact on health and the economy.
Ardern said there were four alert levels to the system.
"Alert level one is where Covid-19 is here, but contained. In this phase we prepare. The basics, like border measures, contact tracing, and cancelling mass gatherings are activated. You'll see that this is where we have been when Covid first arrived in New Zealand.
"Alert level two is where the disease is contained but the risks are growing because we have more cases. This is when we move to reduce our contact with one another. We increase our border measures, and we cancel events. This is also the level where we ask people to work differently if they can, and cancel unnecessary travel.
"Alert level three is where the disease is increasingly difficult to contain. This is where we restrict our contact by stepping things up again. We close public venues and ask non-essential businesses to close.
"Alert level four is where we have sustained transmission. This is where we eliminate contact with each other altogether. We keep essential services going but ask everyone to stay at home until Covid-19 is back under control."
Ardern, who is now based out of Wellington, made another plea for people not to panic-buy, as doing so could deprive others of an item critical to them, such as families that need formula.
"Shopping must continue as normal. Even if we are at alert level four, supermarkets will be open.
"Do not panic-buy at pharmacies. Products will be available."
Asked if New Zealanders were taking Covid-19 seriously enough yet, Ardern said: "They need to."
She rejected the idea the Government was slow to build testing capacity, and Bloomfield added it was important the right people were being tested to avoid unnecessary strain on limited resources.
Public health experts have called for alert four to be put in place already to shut down the threat of an outbreak, but Ardern said there were also public health experts who have backed what the Government is doing.
Concerns about Kiwis on cruise ships
Earlier today, Bloomfield said half of the 56 New Zealanders on the cruise ship Ruby Princess - where four people had tested positive for Covid-19 - had returned to New Zealand, and all of the New Zealanders were being contacted.
But they would not be tested unless they showed symptoms.
Another cruise ship, the Celebrity Solstice, had an Auckland man in his 60s on board who had tested positive for Covid-19.
He joined the ship in Auckland on 10 March and departed the cruise in Dunedin after visiting Tauranga (March 11), Picton (March 13), and Akaroa (March 14.
The ship arrived in Sydney this morning and any New Zealanders on board returning to New Zealand will be regarded as close contacts, put in self-isolation and monitored daily.
Ardern's address today came as the global pandemic marches on. London and the United Kingdom have gone into lockdown and workers in major states and cities in the United States have been told to stay at home.
As the number of confirmed cases rises in New Zealand, libraries, art galleries, museums and university lecture theatres are all temporarily closing their doors.
New Zealand closed its borders to non-residents and non-citizens on Friday, and other countries have gone into lockdown and citizens told to return home. Italy, with 60 million citizens, has recorded 3405 deaths, exceeding the 3248 in China, a country with a population 20 times larger.
It took three months to reach 100,000 coronavirus cases worldwide. The second 100,000 took only 12 days.
Even more major sporting events have been cancelled as health officials tell New Zealanders to practise "physical distancing" whenever they can.
But Ardern has reiterated her call that people should not panic and says New Zealanders should "trust doctors".
Leaders in Auckland and Wellington have moved to temporarily close public places to prevent the virus' spread.
Auckland's art galleries, pools, recreational centres and libraries would all be closed for at least two weeks in response to Covid-19, Mayor Phil Goff confirmed yesterday morning.
This was, as he said, a "necessary step".
He said the moves would not result in any job losses but staff at the public facilities could be redirected into other roles related to the Covid-19 response.
In Wellington, the Te Papa's chairwoman Dame Fran Wilde announced the museum would close for at least two weeks, due to Covid-19.
It was a similar message from Auckland University Vice-Chancellor Dawn Freshwater, who confirmed the university would suspend teaching across its campuses next week.
The university's intention is to be in full digital teaching and learning mode from the week of March 30 onwards.
London shuts down
British Prime Minister Boris Johnson announced the shutdown of London and the UK today.
All pubs, bars, shops, restaurants, gyms and leisure centres across the UK will shut their doors tonight as the Prime Minister unveiled a package of measures to protect workers and the economy.
Johnson urged people not to go out tonight as he introduced the stringent measures, which he said were necessary to "turn the tide" on the epidemic.
The UK Government has also announced "an unprecedented" plan to pay 80 per cent of wages in order to protect workers. The scheme will cover the salary of those on up to £2500 ($NZ5100) a month, just above the median income.
As the number of new UK infections today leapt by 714 up to 3983, Johnson said 75 per cent of the population should stay indoors.