As the world enters its third month of grappling with the fast-spreading coronavirus, one question that has dogged governments and medical practitioners is exactly how dangerous the new disease is.
The World Health Organisation (WHO) this week put the Covid-19 global death rate at about 3.4 per cent - far higher than the seasonal flu's 0.1 per cent - but United States President Donald Trump has cast doubt on its accuracy.
"Well, I think the 3.4 per cent is really a false number," Mr Trump was quoted by The New York Times as saying on Wednesday.
"Now, this is just my hunch... but based on a lot of conversations with a lot of people that do this ... it's very mild," he said. "So, if we have thousands or hundreds of thousands of people that get better just by, you know, sitting around and even going to work - some of them go to work, but they get better."
While he offered no evidence to back up his hunch, some experts noted that it might have some basis.
The WHO's ballpark figure reflects a simple calculation based on the number of deaths and confirmed cases. It does not account for mild, undetected cases.
It is also mostly derived from the experience in China's Wuhan city, the first epicentre of the outbreak, where infections soared before doctors managed to gather the knowledge and resources to battle it.
"Within the rest of China, the mortality rate is, in fact, much lower," Associate Professor Kenneth Mak, director of medical services at Singapore's Ministry of Health, said at a press conference yesterday.
"And perhaps that is a more accurate figure."
WHO has since clarified that the figure is a broad "snapshot" that will change as the outbreak evolves.
Experts expect the death rate to drop considerably when more information is made known about the illness.
Well, I think the 3.4 per cent is really a false number. Now, this is just my hunch... but based on a lot of conversations with a lot of people that do this... it's very mild.
UNITED STATES PRESIDENT DONALD TRUMP
At this point of time, there is nothing to suggest that the virus has changed in its virulence. But what has happened is that those figures have continued to change as more information becomes available.
ASSOCIATE PROFESSOR KENNETH MAK, director of medical services at Singapore's Ministry of Health.
MOST PEOPLE ASYMPTOMATIC
A lot of people are asymptomatic. We're only seeing the cases that are confirmed and the cases of people presenting to the hospital because they can't breathe.
PROFESSOR ROSANNA PEELING, director of the International Diagnostics Centre at the London School of Hygiene and Tropical Medicine.
The 3.4 per cent mortality figure "is certainly an overestimate", said Dr Tom Frieden, former director of the US Centres for Disease Control and Prevention and former New York City health commissioner.
The actual rate will probably be below 1 per cent, Dr Frieden told Bloomberg in an e-mail.
An editorial published on Feb 28 in the New England Journal of Medicine (NEJM) by Dr Anthony S. Fauci and Dr H. Clifford Lane of the National Institute of Allergy and Infectious Diseases, and Dr Robert R. Redfield, director of the Centres for Disease Control and Prevention, arrived at the same conclusion.
"If one assumes that the number of asymptomatic or minimally symptomatic cases is several times as high as the number of reported cases, the case fatality rate may be considerably less than 1 per cent," the doctors wrote.
"This suggests that the overall clinical consequences of Covid-19 may ultimately be more akin to those of a severe seasonal influenza (which has a case fatality rate of approximately 0.1 per cent)… rather than a disease similar to Sars or Mers, which have had case fatality rates of 9 to 10 per cent and 36 per cent, respectively," they added, referring to the severe acute respiratory syndrome and the Middle East respiratory syndrome.
Dr Bruce Aylward, who leads the WHO's coronavirus efforts, expects the fatality rate to turn out between 1 per cent and 2 per cent, The New York Times reported.
Early estimates of the coronavirus death rate in China were about 2 per cent. A more updated report in NEJM based on over 1,000 patients across the country found it to be lower, at 1.4 per cent.
"At this point of time, there is nothing to suggest that the virus has changed in its virulence," Prof Mak said. "But what has happened is that those figures have continued to change as more information becomes available."
In South Korea - the worst-hit country outside of China and where residents are being checked aggressively for the virus - the fatality rate comes in at less than 1 per cent.
More than 6,000 infections have been detected in the country, and at least 40 people have died from it.
Calculations based only on total current cases and deaths are flawed, The New York Times reported Dr Adam Kucharski, a mathematician at the London School of Hygiene and Tropical Medicine, as saying.
He called it a "statistical illusion".
Based on best available data, when adjusted for unreported cases and various delays involved, the fatality risk is probably between 0.5 per cent and 2 per cent for people with symptoms, he said.
About 80 per cent of people infected exhibit only mild symptoms, while some experience none at all, the WHO has previously said.
If many cases go undetected as a result, the virus is able to stealthily spread across communities while evading the WHO's tally, which experts use for analysis.
"A lot of people are asymptomatic," Professor Rosanna Peeling, director of the International Diagnostics Centre at the London School of Hygiene and Tropical Medicine, told Bloomberg.
"We're only seeing the cases that are confirmed and the cases of people presenting to the hospital because they can't breathe."
As some infected individuals also take more time to show symptoms, hospitals around the world may not have been adequately equipped to detect and treat these patients, according to Prof Mak.
Essentially, it is tough to pinpoint the true extent of the coronavirus' lethality until governments get a better grasp of the situation in their countries and share the information transparently.
"We're not too fussed about whether or not (the death rate) changes over time, because we understand that this is in part driven by the statistics that are available," Prof Mak said. "What's important is to focus on our own local efforts to make sure that we detect as early as possible every case that comes on, and that we are able to treat them."
The virus has infected over 98,000 people worldwide and killed over 3,300.
Correction note: A quote by AP Kenneth Mak has been edited for accuracy.