From calling "hysteria" over the outbreak a Democratic hoax, to announcing a national emergency and urging all Americans to work from home and avoid public spaces, US president Donald Trump’s rhetoric on the coronavirus pandemic has shifted significantly in the space of a few weeks.

Trump has come in for heavy criticism from political opponents for what they say was his failure to take the threat of the virus seriously when the outbreak first emerged.

"Thirty five thousand people on average die each year from the flu. Did anyone know that?" Trump told supporters at a rally on February 28.

"Thirty five thousand. That's a lot of people. And so far, we have lost nobody to coronavirus in the United States."

"Now, the Democrats are politicising the coronavirus… this is their new hoax."

But just a few weeks later, Trump’s tone had changed dramatically as he announced a national emergency and urged Americans to take drastic measures to avoid contamination.

"My administration is recommending that all Americans, including the young and healthy, work to engage in schooling from home when possible, avoid gathering in groups of more than 10 people, avoid discretionary travel ,and avoid eating and drinking at bars, restaurants and public food courts," he told the nation this week.