A crowded line of people carrying umbrellas snaked around a hospital in New York City in the rain to access coronavirus testing after the city's health system began diverting patients from the emergency department to nearby tents for testing.

New York City Health and Hospitals is no longer performing tests by appointment and is advising people to stay at home. To decrease pressure on overcrowded emergency rooms, the health system moved testing to outside tents. Its drive-though test sites at Jacobi and Coney Island hospitals have closed.

As of Monday, at least 157 people in the state have died while more than 20,000 people are confirmed to have the virus, accounting for roughly half of all cases in the US.

According to guidance from the city's health department, people who believe they have a mild illness related to Covid-19 should not see their health provider and "will not be tested".

The department says: "Getting tested will not change what your provider will tell you to do to get better. They will tell you to stay home so you do not get others sick."

People will not be tested "unless you are hospitalised and a diagnosis will impact your care", the city says. "Limiting testing protects health care workers and saves essential medical supplies, such as masks and gloves, that are in short supply."

New York City Mayor Bill de Blasio said the city's 11 public hospitals can realistically "only get through this week with supplies on hand" to address the growing emergency as available medical supplies begin to diminish.

Reports of queues outside New York hospitals were incorrectly attributed to lines for emergency care.

He told CNN on Monday: "That's the blunt reality ... If that doesn't come in starting this week, we will get to a point where people can't be saved who could've been saved."

Loading....

His early estimates that the city's health system could manage with its current supplies would get it "safely into April" but now the crisis is "moving so fast I can't even say that anymore".

On Sunday, the New York Police Department began enforcing "social distancing" measures like nonessential business closures and prohibiting team sports from parks.

Governor Andrew Cuomo said the state will be getting more respirators for its frontline health workers, after repeated pleas to the federal government for assistance. The governor has urged Donald Trump to invoke the Defence Production Act to mandate companies to manufacture critically needed personal protective equipment, and to prevent states from competing with one another as well as the federal government for winning bids to receive those supplies.

He said that the state will begin three studies of potential treatments this week, as well as the veracity of blood testing to determine whether a person has contracted the virus and since recovered..