US President Donald Trump has signed an $8.3bn (£6.4bn) emergency bill to combat the coronavirus outbreak.
With confirmed US cases reaching 233 - in addition to 14 deaths - Mr Trump urged calm, adding: "It'll go away."
The White House has faced criticism for its response, and has acknowledged the US does not have enough test kits to meet rising demand.
Results are being awaited of tests on passengers on board a cruise ship being held off San Francisco, California.
Dozens of passengers were tested on Thursday after a passenger died and at least four others became infected on a previous voyage by the ship, the Grand Princess.
More than 100,000 coronavirus cases have been confirmed worldwide and over 3,400 deaths, according to data collated by Johns Hopkins University. The majority of cases and deaths are in China, where the virus first emerged in December.
Stocks in Asia and the UK fell sharply on Friday as investors continued to worry about the broader economic effects of the virus.
What's the latest across the US?
Infections have been reported in 22 states throughout the country.
Thirteen of the 14 US fatalities were from the same nursing home in Seattle, Washington State.
City officials have recommended that Seattle residents aged 60 or older remain in their homes and cancel events with more than 10 people.
On Friday, the University of Washington said it would cancel classes for its 50,000 students - moving teaching online, instead - for the remainder of the winter term, which ends on 20 March.
The majority of US patients remain concentrated on the West Coast - combined, Washington state and California account for 141 of the 233 cases - but infections are now spreading across the country.
In New York, the number of confirmed cases jumped from 22 to 33 in just one day. Governor Andrew Cuomo said that there were 4,000 people under "precautionary quarantines". They were people who have recently returned from places where the outbreak is most severe, including China, Italy, Iran, South Korea and Japan, but do not have any symptoms.
Speaking to media on Friday, Mr Trump repeated his claim that the US cases have been limited "because we have been very strong at the borders".
"In terms of cases it's very, very few," he said.
The government admitted on Thursday that it did not have enough testing kits at its disposal now to meet what is expected to be rising demands in the next few days and weeks.
What is happening with the cruise ship?
California Governor Gavin Newsom has refused to allow the ship to dock until its passengers are properly assessed. Test results are expected later on Friday.
There are 142 Britons among those aboard the ship, which is returning from a voyage to Hawaii after a trip to Mexico last month.
In a statement, the company that operates the ship said samples had been taken from 45 people - both guests and staff - and that all passengers had been confined to their quarters pending the outcome.
A man who sailed on the Grand Princess to Mexico died of coronavirus on Wednesday. The 71-year-old from the Sacramento area had underlying health conditions, officials say.
Two other passengers from that voyage are in hospital with the virus in northern California while two Canadians who recently sailed on the ship tested positive after returning home.
What is happening elsewhere?
- The UK confirms 163 cases of coronavirus - a jump of 48 cases since Thursday
- Egypt records 12 coronavirus infections aboard a cruise ship on the Nile
- The Vatican, Serbia, Slovakia, Peru and Cameroon report their first cases
- Iran's official death toll rises to 124 with 4,747 confirmed cases nationwide
- Italy's death toll rises to 197 after 49 new fatalities on Friday - the country's highest single-day toll so far
- Israel and the Palestinian Authority put the city of Bethlehem under quarantine after seven people are diagnosed with coronavirus
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