At least 3000 Australians could die from the COVID-19 outbreak at a conservative estimate, and the elderly are by far the most vulnerable, infectious diseases specialists warn.

Professor Robert Booy, from the University of Sydney, says in a best-case scenario, about 3000 could succumb to the disease with a worst-case estimate likely involving “many thousands”.

Although the WHO has estimated the fatality rate at 3.4% among confirmed cases, the head of the US National Institute of Health suggests the true rate may be as low as 0.1% because many mild cases circulating in the community remain undetected.

Professor Booy says he has based his estimate on the lower number.