Director-General of Health Dr Ashley Bloomfield said specific details about these cases would be shared later on Wednesday, but he doesn't believe any new cases are associated with schools.

Dr Bloomfield said all of the cases are New Zealanders who have returned from overseas and, of those cases he has detail about, all have been in self-isolation. He said the fact all new cases are associated with travel proves the value of placing restrictions on travel. These border measures would also assist in keeping the risk of community outbreak in New Zealand low.

On Saturday, the Prime Minister announced travel restrictions forcing anyone entering New Zealand from outside of the Pacific Islands to self-isolate for 14 days. Nearly every country around the world has some form of travel restriction. The United States isn't allowing anyone from Europe into the country, while the European Union has closed its external borders.

The 12th coronavirus case was recorded on Tuesday. As reported on Tuesday, they are a student at Dunedin's Logan Park High School and the child of an infected man who recently returned from Germany. That school is now closed and undergoing cleaning.

Dr Bloomfield said on Wednesday there are 150 close contacts for this individual. In addition to going into self-isolation, these individuals will be tested over the next day.

The Ministry of Education's secretary of education Iona Holsted said there are no plans at the moment for widespread school closures. Temporary closures, like at Logan Park, are planned for. She said the risk to children continues to be low.

"Closing schools doesn't stop people meeting," she said.

Holsted said bringing forward school holidays was not a matter of consideration.

However, Dr Bloomfield stressed that restrictions around mass gatherings should be taken seriously and further advice is being considered by the COVID-19 Cabinet Committee. He said authorities were looking at Australia's move to limit gatherings to no more than 100 people.

The Director-General also revealed that police have checked on the compliance and welfare of about 50 tourists meant to be in self-isolation. This involved sighting the individuals and asking a series of questions about their wellbeing. Police are happy with the compliance so far.

There are nearly 200,000 cases worldwide, with more than 7900 dead.

An economic package was revealed by the New Zealand Government on Tuesday to assist businesses and workers adversely affected by the disruption to trade and travel routes. Its also launched a public health campaign to attempt to spread information about the virus and how people can individually combat it.

Mass gatherings of more than 500 people can no longer go ahead, but schools are allowed to stay open.

What we know about coronavirus

Coronavirus is primarily spread through droplets in the air after someone sneezes or coughs. However, it can also be contracted by touching surfaces where the illness is present, according to the World Health Organization. The length of time the virus stays alive on surfaces is unknown at this stage, but some viruses can remain active for days.

The WHO was first informed of cases of the virus in Wuhan on December 31. It was identified as a coronavirus on January 7 and can spread through human-to-human transmission.

"Common signs of infection include respiratory symptoms, fever, cough, shortness of breath and breathing difficulties. In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death," the WHO says.

"Standard recommendations to prevent infection spread include regular hand washing, covering mouth and nose when coughing and sneezing, thoroughly cooking meat and eggs. Avoid close contact with anyone showing symptoms of respiratory illness such as coughing and sneezing."

There is currently no vaccine for the sickness.

How can I protect myself?

avoid touching the mouth, nose and eyes with unwashed hands

washing your hands before eating

carrying a hand sanitiser at all times

being particularly mindful of touching your face after using public transport or going to the airport

carry tissues at all times to cover the mouth and nose when coughing or sneezing (then dispose of it)

not eating shared or communal food

avoiding shaking hands, kissing cheeks

regularly cleaning and sanitise commonly used surfaces and items, such as phones and keys

avoiding close contact with people suffering from or showing symptoms of acute respiratory infection

seeking medical attention if you feel unwell.

A full explainer on protecting yourself from coronavirus can be found here.

The Ministry of Health is reminding the public to get in touch with Healthline on 0800 358 5453 if they have symptoms or concerns.