Trump repeated "We can do two things at once": protect the vulnerable, and get America back to work.

Dr. Birx, an immunologist, noted that the average age of the patient felled by the coronavirus in Italy was 85. There have been younger victims, but they are statistical outliers, as are younger fatalities from ordinary flu virus.

At the briefing Trump was flanked by Response Coordinator for the White House Coronavirus Task Force Deborah Birx, Vice President Mike Pence, and Admiral Brett Giroir.

Trump said that the economic and psychological effects of prolonged economic shutdown could cause its own set of problems and wind up killing many more people. Also present was Attorney General Bill Barr.

It is unprecedented in the United States that almost all business has closed overnight, indefinitely, with millions of people out of work for the foreseeable future, at the same time as a prolonged social isolation is enforced.

In other collapsed economies in which unemployment and hyperinflation reach social crisis levels, such as Venezuela, general lawlessness can set in, in which looting, murder, and rape skyrocket, as police become overwhelmed.

In Dallas, police have informed the public that they will not respond to theft, vandalism, or shoplifting calls.

The effects of another shock during economic chaos, such as a terrorist attack, would be almost unfathomable.

In very urbanized industrial societies, food and other supply chains are fragile, with millions of people depending on trucks to keep rolling and supermarket workers to keep arriving at work.

The effect on the government's finances of trillions of dollars in added debt to pay for a relief package is yet another unknown.

In social breakdowns, the frail and elderly are also the first victims.

Dr. Birx noted that, thus far, the serious cases of the disease seems statistically to spare children. Trump noted that the mortality rate of the coronavirus - the confirmed illnesses which result in death, is far lower than originally reported by earlier data analysis, which at times had the mortality rate up to four percent, but which now seems to be under 1 percent.

Due to a very limited US data set the rate may be much lower, since many who have the virus do not show symptoms and never will. Because the virus enters the "herd" and any people will hav been exposed and never know it, the true denominator of fatalities-to-cases is not known. (Time Magazine: Why COVID-19 May Be Less Deadly Than We Think)

The fatality rate may be further skewed by the fact that tested positive cases now tend to consist of people who are already seriously ill.

The death rate for ordinary flu, for which extensive data is available, is about .1%.

Last month the ordinary flu virus killed approximately 10,000 people in the US. during this year's flu season, with up to 60,000 deaths over the October to March season. Trump said "Many more millions are killed driving cars. We're not going to order stop driving cars."

Trump approved of and urged the nation to follow current guidelines for social isolation.

When pressed by reporters, Trump refused to put a hard timeline on recommending the lifting or easing of the guidelines.

Trump said he was concerned with the effect of the shutdown not only on large companies which employ many people, but on employers and workers in small businesses, which he called the "backbone" of the American economy.

In describing progress on a bipartisan bail-out of US workers and companies for the effects of the shutdown, now being hammered out in Congress, Trump accused Democrats of balking at provisions that would prohibit executives from using the money to engage in stock buybacks.

"I don't like stock buybacks," Trump said, saying the money should be used to help the "worker."

In the financial crisis of 2008, executives at major financial corporations were heavily criticized for using funds from the bail-out packages passed by Congress to perform stock buybacks, and to give themselves bonuses.

Trump also announced that a test of the malaria drug chloroquine would commence in New York City, one of the hardest hit areas, in the coming days. At the same time the US media pounced on the deaths of a couple in Arizona after ingesting a form of chloroquine this week. Trump has cited successes in China with the human-approved drug against the coronavirus, according to an abstract at the US National Library of Medicine National Institutes of Health. The approved human form of the drug is used against malaria, under a doctor's supervision.

But the form of the compound taking by the Arizona couple was not approved for human use, and was fish tank cleaner.

In Nigeria, two other people are reported dead after overdosing from chloroquine, outside of a doctor's supervision.

In a lighter moment of the briefing, as Dr. Birx noted that she herself had been running a mild fever before she was tested negative for coronavirus, Trump casually backed away from Birx.