Authorities in Victoria have said a fourth person has tested positive. A woman in her 20s, who is a resident of Melbourne, is recovering at home with the respiratory illness. The confirmation brings the total number of cases in Australia to 10.
On Saturday morning, Mundine, who rarely strays far from controversy, took to Facebook to put forward his theory on the outbreak.
"I don't even think this Coronavirus is real," he wrote on his Team Mundine page.
"I think it's a ploy to give a mass vaccine, look into it."
Many on his social media gave Mundine short shrift, asking what his qualifications were and if he had a Nobel prize.
"I think you are suffering from a corona induced illness due to the stupid things you say sometimes. The virus is real."
But he also has some fans with one person suggesting the virus crisis had been made up to distract from the slow roll out of 5G technology in China.
It's not the first time Mundine has put forward anti-vaccination conspiracy theories.
In 2019, Paralympian Kurt Fearnley labelled Mundine a "peanut" for "promoting fear" after he shared a video airing discredited claims that vaccines can cause autism.
A Qantas jet is reportedly now on its way to the Chinse ground zero city of Wuhan to evacuate Australians.
The plane will head to the autonomous Chinese territory of Hong Kong first before then heading to the mainland.
Up to 600 people are expected to be evacuated from the city.
This comes after Scott Morrison announced the government's plan to take evacuees from Wuhan to Christmas Island where they would be detained for 14 days.