The global cost of the coronavirus could be three or four times that of the 2003 SARS outbreak, which sapped the world's economy by $40 billion, according to the economist who calculated the SARS figure.

The sheer growth in the Chinese economy over the last 17 years means the global health emergency triggered by the coronavirus outbreak has far greater potential to gouge global growth, according to Warwick McKibbin, professor of economics at the Australian National University in Canberra.

"It's just a mathematical thing," McKibbin said in a phone interview. "Most of the GDP loss that we saw in the SARS model — and in reality — was China slowing down. And so, with China much bigger, you'd expect the billions would be much bigger."