Authorities have called for calm as the number of coronavirus cases in Australia reached 100 on Tuesday.

COVID-19 has infected more than 113,000 people around the world and killed over 4,000, according to CNN's rolling tally.

Health Minister Greg Hunt told reporters in Sydney the COVID-19 outbreak was a "once in a 50 year challenge" but urged Australians to be "patient and understanding".

"Now we are entering a period where there are more people who will be in contact, and more people who will be affected," he said.

"And so this is the moment where, collectively, all of us have to again show that spirit from the summer of supporting each other and recognising that whilst there are challenges, we will absolutely get through this."

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Mr Hunt said expert opinion has been sought on reviewing Italy travel advisories, which are expected to be updated on Wednesday.

He also said it is unlikely people who have recovered would be susceptible to reinfection.

"The broad advice that we have received from the medical experts is that it is highly unlikely that people can be reinfected."

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Chief Medical Officer Brendan Murphy told reporters that Australians still don't need to be tested unless they are a returned traveller, or unless they are a contact of a confirmed case.

"At the moment we are not recommending that general members of the community with acute respiratory symptoms, colds, flu, and the like, be tested," he said.

As of Tuesday, there have been more than 114,000 cases of COVID-19 worldwide and more than 4,000 deaths.