A staff member at a busy Auckland medical centre which treated a woman with coronavirus says the doctor who saw the woman continued working after taking her swabs and only took leave when the results came back positive for Covid-19.

And the staffer at Westgate Medical Centre was concerned they found out about the confirmed case through the news.

The clinic says it followed Auckland Regional Public Health guidelines and the patient didn't make close contact with anyone but the doctor.

It was this morning announced by Health Minister David Clark that there is now a confirmed third case of coronavirus, unrelated to this case.

The woman seen at Westgate Medical Centre had returned to Auckland from a holiday in northern Italy via Singapore on February 25.

On Monday, the Auckland mother flew from Auckland to Palmerston North on Air NZ flight NZ5013, returning on the same day on Air NZ flight NZ 8114.

The Herald understands the woman travelled to Palmerston North for work but returned to Auckland after becoming too ill.

The staff member at the Westgate Medical Centre contacted the Herald because they were concerned more people could now be at risk of exposure.

The medical clinic was itself busy, and located in a busy West Auckland shopping centre.

The staffer was disappointed the medical centre had failed to inform staff that the woman was a confirmed case.

They were also concerned at her first diagnosis at a different clinic where she was prescribed antibiotics - which won't help cure coronavirus - and then sent on her way.

The person now felt an obligation to let the public know that the infected woman had been through the urgent care clinic on Monday.

"The person came in as an urgent care walk-in patient. The clinic does have a protocol, an isolation room specifically designated for people and unfortunately the situation happened in which the patient didn't identify themselves as someone that may have been at risk, even though we do have signage asking people to do that.

"The physician that saw her was unaware of anything until he started talking to her and as a result he was exposed.

"The swab for the coronavirus was done and the results would have come back yesterday [Wednesday].

"I assume he would have been notified being the person that submitted the test, so unbeknownst to me and anybody else at the clinic he left, and was asked to self isolate."

It meant the doctor worked all day Tuesday and part of Wednesday after being exposed.

The Director-General of Health Dr Ashley Bloomfield announcing the second confirmed case of coronavirus at Wednesday's press conference. Photo / Mark Mitchell

"I was pretty upset with the management for not notifying us ... to my knowledge, none of the staff were notified."

They were also upset that the public were being told that the woman would have had "limited contact with people".

"It's a very busy clinic. It's in a big, busy shopping centre so that person would have had contact with a lot of people ... and we as humans touch things. I'm sure she touched the counter to fill out the paper work etc. "

Doctors at the centre could see at least between 20 and 30 patients a day, the staff member understood.

The fact the woman was only exhibiting mild symptoms was not surprising as she was young and fit, the medical centre staff member said.

It is when the virus comes into contact with weakened immune systems - like those often presenting at medical centres, or elderly people, some of whom have several underlying health conditions that people are put in the most danger.

The staff member was saddened to hear the woman's children were now being bullied online but he said she wouldn't have meant any malice in her actions.

The episode was a good reminder for people to know that if they do feel they are showing signs to call a medical centre before going in, so a plan can be arranged for treatment.

The staff member expected the clinic and other medical centres and hospitals to likely become overwhelmed as winter got closer.

As for thoughts on a coronavirus pandemic in New Zealand, he said it was inevitable it will spread.

"The reality is, and I think most who are medically trained realise, that it's inevitable that it's going to happen in New Zealand with it being a place [with high tourism and] most of its population in Auckland which [means it] is going to spread easier with more people in one area."

On behalf of the clinic, Steffan Crausaz, chief executive of Tāmaki Health, confirmed the woman suspected of Covid-19 attended the clinic late on Monday afternoon.

"She presented as a walk-in to urgent care and was seen in a short period of time.

"Once the patient identified herself as having returned from overseas and was showing COVID-19 symptoms, all clinic staff followed Auckland Regional Public Health Service (ARPHS) protocols.

"Because swabs taken by the doctor proved positive for COVID-19, he took leave and will remain at home until 16 March. No other staff were in close contact with the patient so they remain at work."

The affected woman did not need to be hospitalised and was self-isolating at home.

Crausaz said the centre was there to care for patients and communities, "and even more so in challenging times such as with COVID-19".

"We follow public health protocols for managing the care of suspected or confirmed cases of COVID-19. We have signs on the door asking people not to enter if they have been overseas within the last two weeks; they should phone ahead of any visit.

"We continue to assist ARPHS in its efforts to trace and contact any people in the waiting room 15 minutes before the patient arrived to one hour after. We want to assure our patients that the clinic is safe to attend."