At 5.7%, the US currently has the world's highest death rate for the new coronavirus, compared with a global average of 3.4%.

That's most likely because US health officials have prioritized testing only the most severe cases.

New testing standards and more widely available test kits are likely to pick up more mild cases in the US and lower the death rate.

For the latest case total, death toll, and travel information, see Business Insider's live updates here.

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The US has the highest death rate for the novel coronavirus of any country with more than a handful of cases: Based on the official totals of deaths and cases, 5.7% of known patients have died. That's far higher than the global rate of 3.4% that World Health Organization cited on Tuesday — and even higher than mainland China's 3.8%.

Only the Philippines has a higher coronavirus death rate than the US, and it has had only five cases. One of them, a man from Wuhan, China, in early February became the first known fatality outside China.

It's highly unlikely that the coronavirus is more deadly in the US; rather, the number is a product of limited testing in the country.

Widespread testing wasn't possible in the US immediately after the first cases were reported, so the Centers for Disease Control and Prevention held stringent standards for who qualified for a test. Until Wednesday, the agency tested only people who had recent exposure to a confirmed patient, had traveled to a country with an outbreak, or required hospitalization.

So the US still probably has not tested or provided diagnoses to many patients with mild cases.

"There's another whole cohort that is either asymptomatic or minimally symptomatic," Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said at a February 6 briefing. "We're going to see a diminution in the overall death rate."

That's because the death rate is a calculation of the number of known deaths out of the total number of confirmed cases.

Because the disease progresses over a period of weeks, and because these numbers are constantly changing, the death rate is not static and is very likely to continue changing. It is not a reflection of the likelihood that any given person will die if infected.

As of Friday, the US's national coronavirus case count was 263. That included results from state-level coronavirus testing, implemented more widely. The CDC had confirmed only 164 cases and 11 deaths across the country. If you calculate the death rate based on only those federally verified cases, it jumps to roughly 6.7%.

Just one day earlier the CDC had confirmed only 99 cases, resulting in a death rate of 10%. As it confirmed more patients, the death rate dropped.

'Other countries are testing much more broadly than we are'

A swab to be used for testing the novel coronavirus at Harborview Medical Center in Seattle. David Ryder/Reuters

Because flawed tests and limited funding initially meant testing capacity in the US was restricted, the CDC has tested about 1,583 people in the US. That does not include state and local testing.

Alex Azar, the US secretary of health and human services, told ABC on Sunday that 3,600 Americans had been tested in total.

South Korea, by contrast, has implemented free coronavirus-testing drive-thrus and tested more than 164,000 people. The country's death rate at the moment is just 0.6% — 42 deaths out of a total of 6,593 reported infections. (The death rates in all countries are constantly evolving, in fact, as patients' illnesses progress and as more people receive diagnoses.)

"Other countries are testing much more broadly than we are," William Schaffner, an infectious-disease specialist at the Vanderbilt University School of Medicine, previously told Business Insider. "We are trotting along while they're racing along."

Medical staff taking samples from a driver with symptoms of the novel coronavirus at a "drive-thru" virus test facility in Goyang, South Korea, on Sunday. Ahn Young-joon/AP

To be sure, the US has a much lower case count overall than either South Korea or China, so any death significantly affects the country's fatality rate. But again, the low case count is probably due to how few people have been tested.

"I'm in coronavirus briefings with groups of experts as well as members of Congress and the military," Matthew McCarthy, a hospitalist at Weill Cornell Medicine in New York City, tweeted on Sunday. "These meetings are contentious, but there's one thing we agree upon: Coronavirus has been circulating in the United States for weeks. We didn't detect it because we weren't testing properly."

The CDC changed its testing standards this week

The CDC's new testing standards are much more open-ended, saying "clinicians should use their judgment" to determine whether patients should be tested for the new coronavirus.

US officials also said they were working to distribute more tests. Azar told ABC on Sunday that "we now have 75,000 tests available." He added that over the week testing would "expand radically."

"The estimates we're getting from industry right now — by the end of this week, close to a million tests will be able to be performed," Dr. Stephen Hahn, the commissioner of the Food and Drug Administration, said at a White House press briefing on Monday. On Thursday, however, senators briefed on the matter said that timeline was unlikely, according to Bloomberg.

Some experts say the US government should have taken steps to ramp up testing weeks ago.

A staff member blocking the view as a person was taken by a stretcher to a waiting ambulance from a Washington state nursing facility where more than 50 people were sick and being tested for the COVID-19 virus on February 29. Elaine Thompson/AP

"It is well within the realm of possibility that there are 100,000 people infected with this right now in the United States," the Yale professor Howard Forman, a radiologist who is an expert in healthcare management, told Business Insider. "Healthcare providers may be being exposed, other patients may be being exposed, and until you can give confidence to people about those answers, we are in a crisis here."

Aria Bendix, Aylin Woodward, and Jessica Snouwaert contributed reporting.