A top US health official says Americans should prepare for nearly two months or more of shutdowns and working from home as the deadly coronavirus spreads throughout the country.

“It’s certainly going to get worse before it gets better,” Dr Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases with the the National Institutes of Health, said during an interview on Good Morning America.

He continued to say Americans could see “eight weeks or more” of shutdowns and working from home as the virus surges in communities across the country.

The Friday morning warning came just days after the World Health Organisation declared the outbreak to be a pandemic, and after Donald Trump announced a travel ban on non-Americans travelling to the US from Europe.

There have been over 1,700 confirmed cases of the virus in the United States so far, although critics have suggested the rate may be much higher. A shortage of testing kits have led some to note that there may be many more people infected, but it would be impossible to know for sure without confirmation.

There have been 40 deaths from the virus in the United States, including 31 in Washington State — which has so-far been the epicentre of the outbreak in the country — as well as four dead in California, tw dead in Florida, one dead in New Jersey and one dead in Georgia.

The warning from Dr Fauci represent something of an escalation in urgency for the health official, who days ago noted that Americans need to be prepared for a crisis, but said he does not think the US would implement an air tight block on travel into and out of the country.

"We have to be realistic. I don’t think it would be as draconian as nobody in or nobody out," he said.