The United States now has more than 100,000 confirmed cases of the new coronavirus, a tracker maintained by Johns Hopkins University showed Friday.
There have been 100,717 cases including 1,544 deaths as of Saturday morning Australian time.
The biggest cluster by far is in New York, home to almost half the cases, overwhelming the hospital system.
The United States has around 15,000 more confirmed cases then the second country on the list, Italy, and 20,000 more than China, where the disease was first identified but has since peaked.
The US death rate based on confirmed cases is about 1.5 per cent, compared to around 10.5 per cent in Italy.
This death rate figure could fall, as greater testing reveals more people who are positive but asymptomatic.
It may also rise if more cities and states find themselves in a similar position to New York, which has seen more than 500 deaths and is experiencing a drastic shortage of hospital beds, personal protective equipment and ventilators.
"We're still seeing a rising number of cases, a rising number of hospitalizations, rising number of intensive care unit admission, a rising number of patients with the mechanical ventilators," Thomas Tsai, a professor of health policy at Harvard told AFP.
A cleaner in Boston Source: Getty Images
"And unfortunately, the death rate is likely going to follow that pattern. It's just that it's going to be days or weeks behind."
How did the US get to this stage? And what happens next?
Testing, testing, testing
Public health experts say that while the US yet to hit the peak of the epidemic, there are several reasons why the COVID-19 disease has exploded in America.
Early on in the outbreak, President Donald Trump was accused of downplaying its severity, saying that sustained community spread was not "inevitable" even after a senior health official said it was, which could have led to a sense of complacency.
As the illness took root, first in the West Coast states of Washington and California, the US was unable to perform meaningful levels of contact tracing because it was so slow off the mark with testing.
The government initially refused to relax regulatory hurdles that would have allowed states and local health departments to develop their own test kits based on guidelines provided by the World Health Organization, and all early samples were being sent to the headquarters of the Centers for Disease Control and Prevention (CDC) in Atlanta.
A certified registered nurse talks to a patient in their car at Penn State Health St. Joseph where they are conducting drive through coronavirus testing Source: Getty Images
Then the CDC sent out faulty test kits to the states, adding to delays.
It was not until 29 February, the date of the first US death and more than a month after the first confirmed US case, that the government lifted its ban. The private sector entered later, adding to capacity.
"If we could have done contact tracing, we might have found a lot more cases quickly and shut down the hotspots," Gabor Kelen, director of emergency medicine at Johns Hopkins University, told AFP.
US officials have defended their response, repeatedly asserting that tests developed by South Korea -- which is seen as an example of best practice for its aggressive early testing -- sometimes produced false positives.
Kelen disagreed with that reasoning.
"One thing I teach my residents: Something is better than nothing, sooner is better than later, and if one test is good, two are better. So let's get to it - perfect is the enemy of good," he said.
No national response
Densely populated New York has emerged as the US epicentre of the outbreak, with almost 45,000 cases as of Friday - about half the US total - and over 500 deaths.
Neighbouring New Jersey follows, then California and Washington state, then Michigan and Illinois in the Midwest, with clusters focused in major cities.
States or areas that have yet to experience surges should not be complacent, said Thomas Tsai, a general surgeon and professor of health policy at Harvard.
A handful of people walking in New York City Source: Getty
"The United States isn't one monolith, there are 50 different states with different government responses from governors and state public health departments," he told AFP.
"I think what's needed is a truly national coordinated effort," said Tsai, warning that continuing with a "patchwork response" on people's movements would lead to other states seeing the types of surge experienced in places like New York.
As of Friday afternoon, 61 per cent of the US population of 330 million was called to lockdown, meaning 39 per cent is not.
What now?
One relative bright spot has been that the fatality rate in the US based on confirmed cases has remained relatively low so far - 1.5 per cent, compared to 7.7 per cent in Spain and 10 per cent in Italy.
Will this trend continue? The short answer is we don't know, and the experts are divided.
"Low CFR (case fatality rate) is not reassuring," David Fisman, an epidemiologist at the University of Toronto, told AFP.
"It will rise because it takes people time to die. My best guess is that the US is on the cusp of an absolutely disastrous outbreak."
US President Donald Trump speaks during the daily briefing on the novel coronavirus, COVID-19, in the Brady Briefing Room at the White House Source: AFP
The experts agreed that nationwide social distancing measures were urgently needed to continue to try to "flatten the curve" -- slowing the rate of infection so that hospitals aren't overrun, as the case is currently in New York.
But from a scientific point of view, the pathogen could "down mutate" and become less virulent as time goes on, said Kelen, as similar viruses typically do.
The heat and humidity of summer could also slow its spread, experts have said.
Forecasters at the University of Washington's School of Medicine believe the peak of the outbreak may come in mid-April.
The number of deaths would keep rising but then plateau at over 80,000 by July.
Their model suggests 38,000 deaths at the lower end and 162,000 at the higher end.
By way of comparison, influenza killed 34,000 people in the 2018-2019 flu season.
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If you believe you may have contracted the virus, call your doctor (don’t visit) or contact the national Coronavirus Health Information Hotline on 1800 020 080.
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