A Melbourne doctor who treated at least 70 patients at his clinic and saw two others at a nursing home has been diagnosed with coronavirus, sparking fury and concern.

The man, a GP aged in his 70s, became unwell on a flight from the United States to Australia at the end of a holiday, but went back to work at The Toorak Clinic in Toorak for five days anyway.

He was last night diagnosed with the potentially deadly virus and Victorian Health authorities have been in touch with those who came in contact with him, ordering them to self-isolate for 14 days.

"I have to say I am flabbergasted that a doctor that has flu-like symptoms has gone to work," the state's Health Minister Jenny Mikakos said.

The man became unwell on a flight from Denver, Colorado to San Francisco in California on February 27, and then flew on to Melbourne on United Airlines flight 60, arriving on the morning of February 29.

On Monday, he went to work at The Toorak Clinic on Malvern Road in the suburb of Toorak and saw at least 70 patients between then and Friday.

"Patients have been contacted via text message this morning, or were called this morning, they will be followed up with emails," Ms Mikakos said.

"This doctor also attended two patients at a nursing home in Malvern during that time. The two nursing home patients have been isolated in their rooms and the department is working to provide support care for these residents."

The doctor is now recovering in isolation but his decision to keep working when he was clearly ill has sparked anger from the government.

"I understand our medical and healthcare workers are dedicated to the work they do," Ms Mikakos said.

"But it is irresponsible for people to be going to work if they are unwell, and that is not just healthcare workers, it is everybody in the community who needs to take this very seriously."

Federal authorities are also working to obtain the passenger manifest from the flight the man was on, so those who came in contact with him on board can be contacted, she said.

"Passengers will be contacted as soon as it is made available."

Meanwhile, Ms Mikakos announced that two international students at a school in Shepparton have tested negative for the virus.

There are now 11 confirmed cases in Victoria, bringing the total number across Australia to at least 65.

New South Wales now has the highest number of cases with 28 infected, while there is one confirmed case each in Northern Territory and Tasmania.

South Australia has seven confirmed cases while Queensland now has a total of 14 confirmed cases.

A 28-year-old man in Queensland who reportedly flew from Iran to Australia is the latest person to test positive for coronavirus.

"A 28-year-old male is in a stable condition and is being transferred from his home in Brisbane to the Princess Alexandra Hospital," a Queensland Health statement said.

"He has recently returned from Iran and contact tracing is underway."

Almost 3000 Queenslanders have been issued notices asking them to voluntarily self-isolate since the coronavirus outbreak in Australia.

Three of Queensland's confirmed cases were on the virus-hit Diamond Princess cruise ship.

On Saturday, health authorities in Victoria reported a new case - taking the state's total to 11 - but no further details were available.

NSW Health on Friday confirmed three new cases of COVID-19, bringing the total number of positive cases to 28 in the state since the outbreak began.

Two of the new cases, a 24-year-old female and 21-year-old male, are both staff members at the Dorothy Henderson Lodge Aged Care Facility.

Four residents and three staff members have now been confirmed as cases at the facility to date. A 94-year-old female resident passed away earlier this week and subsequently tested positive to COVID-19. The family of the elderly woman have all tested negative.

The latest case in NSW to be diagnosed, the 28th person, is an 18-year-old female. She is a household contact of another recent case in Western Sydney.

An overnight case, a 16-year-old student from Epping Boys High School, was admitted to The Children's Hospital at Westmead and is in a stable condition. His mother, who works at Ryde Hospital, has undergone testing but is currently well. Several other family members have also undergone testing with results expected tomorrow.

Figures come from the Johns Hopkins University Center for Systems Science and Engineering.

Meanwhile, Australia's panic for toilet paper appears to have spread overseas, with supermarket shelves also emptying across Britain and the US.

Australia's toilet paper crisis reached fever pitch when photos of empty shelves and stuffed trolleys went viral on social media this week.

One shopper told news.com.au they were stocking up because everyone had gone "a little bit crazy".

"I'm buying it because everyone else is doing it," another said.

More than 60 cases of the virus have now been reported across the country and two people have died.

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On Friday, Prime Minister Scott Morrison said the outbreak could cost Australian taxpayers about $1 billion in health spending.

Across the world, there have been more than 100,000 confirmed cases of coronavirus and more than 3,300 reported deaths.

On Friday, shoppers complained of bare aisles and people hoarding loo roll in grocery stores across the UK, including Tesco, Sainsbury's and Morrisons.

Shortages of hand soap, disinfectants, baby wipes, pasta and rice were also spotted in stores.

Boots - one of the UK's biggest pharmacy chains - has advised that hand sanitiser is sold out in some of its stores and will be rationed in others. Signs posted on shelves also warned face masks were unavailable.

The British Retail Consortium, which represents most of the UK's supermarkets, told news.com.au there had been a "rise in demand" for both hygiene and long-life products.

"Our members are working as hard as they can to ensure all consumers have access to the products they need," the director of food and sustainability, Andrew Opie, said.

In the United States, police were called to a Costco in California on Friday after customers became "unruly" over shortages of toilet paper, water and paper towels.

Kroger Co, the biggest independent grocer in the US, has also placed limits on the number of "sanitisation" and "cold and flu-related" products people can buy.