Trump's administration said the existing travel ban on Iran would extend to foreign nationals who had been in the country the past 14 days. The State Department also ratcheted up its warning ,advising Americans not to travel to parts of Italy and South Korea affected by the virus.
Trump said additional cases are likely in the United States but said the illness will be survivable for the vast majority who contract it. He called for calm and said he will meet at the White House on Monday with representatives of major drug companies about an accelerated vaccine.
Vice President Mike Pence said the risk to most Americans remains low.
Pence and Trump addressed reporters in a hastily-called news conference at the White House. Trump assured Americans that "our country is prepared for any circumstance."
Meanwhile, the Food and Drug Administration expanded coronavirus testing by speeding up hospitals' abilities to test, though some worried the changes fell short in reducing logistical burdens.
Alarm has spread in the US since late yesterday when health officials in Washington state, Oregon and California reported new cases among people who have not travelled recently to countries hit hard by the outbreak, or come into contact with anyone known to have the disease, which public health officials refer to as community transmission.
The four new cases announced yesterday bring the total number of covid-19 cases detected through the US. public health system to 19, according to the Centers for Disease Control and Prevention.
Washington state announced late yesterday that a high school student in Snohomish County, just north of Seattle, tested positive for the deadly virus and was in home isolation in a suspected community transmission case.
Earlier in the day Oregon health officials reported a presumptive positive test in an elementary school employee with no known travel history or contact with infected individuals. California also reported a second case of community transmission, in Santa Clara County, after reporting the nation's first such case, in Solano County, earlier in the week.
The Washington State Department of Health and health officials from Seattle and King County said they would offer more details on the first US death related to coronavirus at a 1pm local time news conference.
More coronavirus infections were additionally reported internationally from South Korea to France to Qatar on Saturday. Iran reported more than 200 new cases of the virus causing covid-19 - as well as nine deaths, adding to the highest death toll from the virus outside of China.
China reported its lowest manufacturing numbers on record for the month of February, as the epidemic-stricken economy ground to an unprecedented standstill.
France banned gatherings of more than 5,000 people after the Health Ministry confirmed 19 new cases late on Friday, a nearly 100 per cent increase since the day before.