The looming global coronavirus pandemic could break out in Australia at the peak of the winter flu season, as experts warn that it is possible to be infected with both potentially lethal respiratory illnesses at the same time.

Brett Sutton, the state's Chief Health Officer, said Victorians who fall sick this flu season are likely to be tested for coronavirus and influenza at the same time.

Chief Health Officer Brett Sutton says more cases of coronavirus in Australia are 'inevitable'. Credit:Joe Armao

"We have to bear in mind that the pickup in coronavirus cases and the flu season might coincide," Dr Sutton said. "It may well be that we have respiratory clinics seeing both flu patients and coronavirus patients."

It comes as Prime Minister Scott Morrison declared on Thursday that Australia was activating its pandemic plan as the coronavirus spreads to 42 countries across the world.