New York: US president Donald Trump warned Americans that the country is headed into a few brutal weeks ahead where "there will be a lot of death", and also circled back to his riff on reopening the economy as the coronavirus death toll surged past 8,400, overwhelming the domestic health care system.

"There will be a lot of death, unfortunately. There will be death", Trump said at a White House briefing on Saturday.

"This country was not designed to be closed. The cure cannot be worse than the problem", Trump said even as the country's top infectious diseases experts pleaded with Americans to strictly follow social distancing guidelines in place from March 16.

"This is the moment to do everything that you can listed on the presidential guidelines," Dr. Deborah Birx, White House coronavirus coordinator, urged Americans as the country's caseload climbed to more than 300,000.

"This is the moment to not be going to the grocery store, not be going to the pharmacy, and keeping your family safe. That means everybody doing the six feet distancing, washing your hands", she said.

America's foremost medical leaders on the US coronavirus task force are clear that "physical separateness" is the most crucial behaviour needed to blunt the alarming curve of the virus spread in the US.

The next two weeks are "incredibly important", Birx cautioned. The worst hit from the outbreak is likely in the coming 7-10 days, especially in the country's top two hotspots of New York and New Jersey.

Based on the predictive models the US government is using, New York's peak toll of 855 deaths on a single day is likely around April 10. As on date, New York is facing a shortage of more than 60,000 hospital beds to handle that projected peak load and is falling short of at least 11,000 intensive care unit beds. It's what New York governor Andrew Cuomo is calling the "battle at the top of the mountain", referring to the steep bell shaped curve of the predictive model.

New York and New Jersey are reporting 35 percent of their tests are positive. Louisiana follows close behind with a 26 per cent positive rate. Michigan, Connecticut, Indiana, Georgia and Illinois are at 15 per cent while Colorado, Washington DC, Rhode Island and Massachusetts are all at 13 per cent. Detroit and Pennsylvania are also beginning to look "concerning", according to Birx.

"As sobering and a difficult as this is, what we are doing is making a difference," Fauci said. But even as Fauci urged Americans to be patient and let mitigation efforts work, Trump said: "Mitigation does work. But again, we're not going to destroy our country."

Fauci returned to his earlier note of caution that America will see deaths continue to go up in the coming week or two. That, he said, "is really a cascading of events where you see new cases, hospitalisation, intensive care and deaths."

Effective mitigation, Fauci said, tracks back to the number of new cases. "We're going to pay close attention to that."

Fauci remains hopeful that the social mitigation measures currently in place in the US will be able to blunt the attack rate.

Even as Trump kept coming back to strategies that could put the country back to work, Fauci emphasised how countries which followed a strict mitigation succeeded in blunting the curve.

"Washington got hit really early and they put in a strong mitigation program. They're still down there on the charts, doing well", he said as Trump looked on.

Fauci has for long focused him messaging around what he calls the "two opposing forces" of the virus' path across societies and social distancing measures.

"The virus wants to do what the virus wants to do. Viruses transmit from people to people. When people are separated from each other, virus does not transmit. It doesn't go anywhere.

"As sobering and a difficult as this is, what we are doing is making a difference," Fauci said.

According to Fauci, the "ultimate solution" to a virus that might keep coming back is a vaccine and that, he has said, will take 12-18 months.

The Trump administration estimates that coronavirus will kill 100,000-200,000 people in America even with full mitigation measures in place.