Test results for 150 students of Dunedin's Logan Park High School have all come back negative, as New Zealand counts 28 coronavirus cases.

The Ministry of Health confirmed all the students were cleared of Covid-19 on Thursday afternoon, after coming into contact with a confirmed case earlier in the week.

On Thursday, eight new cases of Covid-19 were confirmed, bringing the total to 28 confirmed cases in New Zealand.

One person had been hospitalised for the virus, and the remaining seven were recovering in self-isolation, Ministry of Health director-general of health Dr Ashley Bloomfield said during a Thursday press conference.

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Two of the new cases are in Taranaki, one in Queenstown, one in Dunedin, one in Rotorua, two in Auckland, and one in Northland.

These new cases related to overseas travel, with people returning from Egypt, France, Spain the United States and England.

Two of the new confirmed cases of coronavirus in Taranaki were a male and female both in their 40s who recently visited Egypt. Neither attended the Womad festival on the weekend of March 14.

The Rotorua case was later confirmed by Toi Te Ora, the public health unit for both Bay of Plenty and the Lakes District, to be a French national who was tested prior to arriving in the town.

The man had arrived in New Zealand on March 13, and was now in self-isolation.

The Spanish man, in his 60s, is unwell and being cared for at Lakes District Hospital in Queenstown. His wife is being tested and is self-isolating. Contact tracing has commenced.

The Dunedin woman, in her 30s, had recently travelled to Australia and the United Kingdom, via Los Angeles. She has mild symptoms and has been self-isolating since returning to New Zealand this week.

KEVIN STENT/STUFF Hospital staff outside Wellington Hospital A&E department, where they are monitoring people inside the foyer.

Close contacts of the latest cases were being traced and contacted, and would be required to self-isolate.

For people on the same flights as the confirmed cases, close contacts were considered to be those sitting in the two seats in any direction of the case.

"We are expecting more [cases] given the rapidly evolving situation overseas," Bloomfield said.

HAGEN HOPKINS/GETTY IMAGES Ministry of Health's Director-General of Health Dr Ashley Bloomfield.

Addressing rumours of a full shutdown of the country, Bloomfield said this was not something he had heard being discussed.

Recent modelling showed that, even when working to "flatten the curve" of transmission, the health system would be overwhelmed with coronavirus cases.

KEVIN STENT/STUFF Coronavirus spreads via droplets from the nose or mouth expelled when a person with the disease coughs, sneezes or exhales. (File photo).

"Our aim is to stop it getting to that point, where the peak is higher than our health system's ability to cope," Bloomfield said.

"We're preparing to take all the measures we need to make sure we don't get wider community spread ... We have shown that we are prepared to act early."

Bloomfield said the same self-isolation advise applied - "fundamental to New Zealand's response is not putting others at risk. If you are unwell, please do not go to work".

"Confirmed cases of Covid-19 who are in strict self-isolation can and should maintain that two metre distance from others in their household," he said.

A third of workers at the Ministry of Health would be working at home from next week to ensure the organisation's business continuity planning was working.

On Wednesday, Bloomfield said there were 30,000 swabs for coronavirus tests being distributed across the country.

Further testing measures — both community testing centres and "sentinel testing" run at certain GP clinics — were also being rolled out.

People who have been in or transitted through any country other than those in the Pacific islands or have been in close contact with someone with coronavirus must self-isolate for 14 days. They should also register with Healthline (0800 358 5453).

People who display symptoms should phone Healthline in the first instance - don't head straight to your doctor or medical centre.

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Latest cases

- A Taranaki woman in her 40s, who arrived in New Plymouth on March 9 from Cairo to New Plymouth via Dubai on Emirates flight EK926, Auckland on Emirates flight EK448 and Air New Zealand flight NZ8041 to New Plymouth.

- A Taranaki man in his 40s, who arrived in New Plymouth on March 15 from Cairo via Frankfurt (Lufthansa LH581), Vancouver (Air New Zealand flight NZ23) and Auckland on Air New Zealand flight NZ8035.

- A Northland man in his 20s, who arrived in Auckland on March 16 from Paris to Abu Dhabi on Etihad flight EY38 on March 14, to Sydney (Etihad flight EY450) on Virgin Australia flight VA0141.

- A Rotorua man who arrived from France on March 13.

- An Auckland man in his 60s, who arrived in Auckland on March 13 from Los Angeles via Air New Zealand flight NZ05.

- An Auckland man, who arrived in Auckland on March 15 from London to Singapore flight QF2 on March 13 to Melbourne (flight QF36 on March 14) to Auckland on Qantas flight QF153.

- A Spanish man, in his 60s, is unwell and being cared for at Lakes District Hospital in Queenstown. His wife is being tested and is self-isolating. Contact tracing has commenced.

- A Dunedin woman, in her 30s, had recently travelled to Australia and the United Kingdom, via Los Angeles. She has mild symptoms and has been self-isolating since returning to New Zealand this week.