US President Donald Trump has declared a national emergency to help handle the growing outbreak of coronavirus.
The order allows the federal government to tap up to $50bn (£40bn) in emergency relief funds to help state and local health officials.
The move loosens medical insurance regulations, and could speed up the creation of new hospitals and the search for new treatments.
There are 1,701 confirmed cases of Covid-19 in the US, and 40 deaths.
Several US states have taken measures to stem the inflation rate, including banning large gatherings, sporting events and closing schools.
The virus originated in China last December, but Europe is now the "epicentre" of the global pandemic, the head of the World Health Organization has said.
Dr Tedros Adhanom Ghebreyesus urged countries to use aggressive measures, community mobilisation and social distancing to save lives.
His comments came as several European countries reported steep rises in infections and deaths. Italy has recorded its highest daily toll yet - 250 over the past 24 hours, taking the total to 1,266, with 17,660 infections overall.
Mr Trump's administration has come under recent scrutiny over its failure to provide Americans with widespread coronavirus testing.
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Democrats in Congress and heavily-affected states had been urging Mr Trump to issue the order, which will also allow more people to qualify for government health insurance.
The decision on the state of emergency was announced by Mr Trump in a live address from the White House.
Mr Trump has himself been urged to explain why he hasn't taken a coronavirus test following reports that he has been in the company of people who have tested positive recently.
In Canada, Prime Minister Justin Trudeau began a 14-day self-isolation period on Friday after his wife tested positive.
Brazil's President Jair Bolsanaro has tested negative, despite one of his top aides falling sick recently. Both men had recently met US officials including President Trump and Vice-President Mike Pence.
President Trump's travel ban on 26 European countries, which was met with anger and confusion. this week, will go into effect on Friday at midnight EDT (04:00 GMT on Saturday).
What is a national emergency?
The 1988 Stafford Act gives the president alone the ability to direct the Federal Emergency Management Agency (Fema) to co-ordinate a national response to "natural catastrophes" within the US.
Mr Trump has declared several national emergencies in his presidency, most controversially invoking the law to direct the US Defence Department to build a southern border wall to prevent illegal immigration.
He has also issued the order to deal with wildfires in California and flooding in the Midwest.
It marks the first use of the order to fight a pandemic since President Barack Obama issued one to fight the swine flu virus.
President Bill Clinton issued a national emergency to pay for efforts to stop the spread of West Nile virus in the US northeast.
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