Thirteen cases of coronavirus have been confirmed in NSW in what has been described as an increase in diagnoses of the virus.

“We believe that they first presented to their GPs and that they were then able to have their pathology results,” Health Minister Brad Hazzard told reporters on Tuesday afternoon.

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Earlier on Tuesday afternoon, Premier Gladys Berejiklian confirmed that a 39-year-old man who had flown in from Iran had become the 10th confirmed case of COVID-19.

Soon after, Hazzard became aware of a further three cases.

“Reflecting what is happening worldwide, and obviously an increasing number of people are being diagnosed with the coronavirus, what we are now seeing in Sydney is reflective of that situation,” he said.

“We are seeing a clear escalation in diagnoses of the virus.”

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A 53-year-old man who had flown in from Singapore became the state’s 11th case of COVID-19.

The 12th person in NSW to have contracted the virus was a woman in her 60s who had recently returned to Australia from South Korea.

She was also diagnosed on Tuesday afternoon.

Authorities are working to find out which flight she was on.

Mask-wearing commuters walk the streets in Beijing, China on March 3. Credit: Koki Kataoka / AP

Another woman, also in her 60s, had recently returned from Japan.

She, too, was diagnosed on Tuesday - becoming the 13th person in NSW to have coronavirus.

Be cautious, not alarmed

NSW Chief Health Officer Dr Kerry Chant said that despite the rise in cases she was “pleased” with the situation.

“I think, with the evolving situation overseas, it gives me confidence that people are presenting to GPs,” she said.

Tourists wearing face masks in Paris. Credit: Chesnot / Getty Images

“Thank you to the GPs who undertook the testing and thank you to the patients who recognised they were at higher risk and have come forward for testing.”

Chevron Right Icon ‘Thank you to the patients who recognised they were at higher risk and have come forward.’

Hazzard said that despite the increase in diagnoses, those infected are “generally doing reasonably well”.

“Their presentation (to doctors) can be on mild symptoms, and early information we have on the four latest cases today is that they came through GPs,” he said.

‘Necessary pathology‘

“They were very sensible, their GPs arranged necessary pathology and they went home and self-isolated. They’re actually doing quite well.

“On a clinical basis ... the patients may not require ICU treatment. That may be reserved for particular patients.”

FILE | A man wearing a face mask in Australia. Credit: AAP

The health minister added that, on average, around 80 per cent of those diagnosed only have “fairly mild symptoms and tend to recover fairly well”.

Chevron Right Icon ‘Once you’re in the care of our doctors and nurses you are extremely well cared for.’

He advised that Australians could take comfort in the nation’s “amazing” healthcare system.

“Once you’re in the care of our doctors and nurses you are extremely well cared for,” he said.

Update on healthcare worker

Hazzard and Chant also provided an update on what is believed to have been one of the first cases of human-to-human transmission of the virus in Australia.

On Monday, it was confirmed that a male health care worker who had not been overseas for at least three months had tested positive.

He was working at Ryde Hospital but had not cared for any coronavirus patients, Chant told reporters on Tuesday.

NSW Health is working to find out which staff and patients were in close proximity with him and the investigation is “progressing quite well”.