A number of US states have ordered shutdowns with one in five Americans soon set to be under a “stay at home” order.
Connecticut and New Jersey on Friday joined Illinois and California in ordering residents to stay at home in order to combat coronavirus.
New York State ordered non-essential businesses to close.
The virus has claimed nearly 230 lives in the US and infected more than 18,500 people.
Globally more than 275,000 patients have tested positive for the respiratory illness and more than 11,000 have died.
A ban on non-essential travel across the US-Canada border came into effect at midnight on Saturday.
Speaking at the White House later in the day, President Donald Trump said governors, mayors and citizens were working with “urgency and speed” in what he described as a “war against the virus”.
Also at the news conference, Vice-President Mike Pence said he and his wife would be tested after one of his aides tested positive for the virus.
“Neither the president or I had direct contact” with staffer, Mr Pence said, adding that the staffer was “well”.
