One medical expert with experience in pandemic planning said social distancing 'works well when introduced early.'

Canada's finance minister said that while the impact right now is unclear, the effects of the novel coronavirus outbreak could be "significant."

Officials finally began to seal the borders on Jan. 23. But it was too late. Speaking to reporters a few days after the the city was put under quarantine, the mayor estimated that 5 million people had already left.

"We've offered to help China with medical supplies," said Rob Oliphant.

But Health Minister Patty Hajdu said quarantine would only be used on advice of health officials.

China’s worst health crisis in years has sparked fear and uncertainty for businesses from North America to Asia that depend on trade in the affected region.

Wuhan and a number of surrounding municipalities are under lockdown, with travel networks and services shut down or restricted.

The mysterious lung virus is part of a large family of coronaviruses with a wide range of severity.

At least eight cities have been shut down —- Wuhan, Ezhou, Huanggang, Chibi, Qianjiang, Zhijiang, Jingmen and Xiantao — all in central China’s Hubei province, where the illness has been concentrated.