A principal who returned to school after a visit to coronavirus-hit Italy is assuring parents their kids are not at risk.

Claire Amos, principal of Albany Senior High School on Auckland's North Shore, posted a statement on Facebook on Monday evening saying she was embarking on 14 days of isolation.

Amos arrived back in New Zealand on Sunday from Bologna in northern Italy, which is two and a half hours from the country's coronavirus epicentre.

She went to school as normal on Monday morning, in accordance with government guidelines, which at that point did not place any restrictions on arrivals from Italy.

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That changed on Monday afternoon, when the Government updated its travel guidelines, advising travellers returning from South Korea and northern Italy to self-isolate.

The number of deaths in Italy due to the virus is currently 52, with the number of confirmed cases sitting at 1835.

Amy Baker/Stuff The principal of Albany Senior High School has self-isolated after returning from Italy.

Amos assured parents that she was not in close contact with any students during her time at school on Monday.

"[I] do not believe my being at school posed a risk to any of our staff, students, or community members."

She said it was important as a school leader that she took all precautionary measures seriously and reassured parents that she was in "excellent health".

"There is no reason for our students, staff, or community to be concerned at this stage," she said.

Amos told Stuff she had been "heartened" by the response from the school community.

"[They] have shown their support and understanding of how we have responded to such a complex and evolving situation."

She said she would continue to work from home for the next two weeks: "On a personal level, I'm doing fine and just thankful for living in a time when it is so easy to stay connected remotely".

CHRIS MCKEEN/STUFF Prime Minister Jacinda Ardern said travellers had been complying with self-quarantine guidelines.

On Sunday, Prime Minister Jacinda Ardern said reports so far indicated that Kiwis were complying with self-quarantine guidelines.

Health officials were even seeing overcompliance, she said, with some people not leaving isolation after 14 days.

On Monday, China and Iran had their travel restrictions extended for another week.

New Zealand's first case of coronavirus was confirmed on Friday and a person in their 60s is currently in Auckland Hospital.

Two more people in New Zealand were being tested and authorities were "highly suspicious" they have contracted coronavirus, the director-general of health, Dr Ashley Bloomfield said.

About 146 tests, on people all around the country, had come back negative and 12 were under investigation, he said.