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The pandemic’s big mystery: How deadly is the coronavirus?

Published : Monday, 6 July, 2020 at 12:00 AM  Count : 487

More than six months into the pandemic, the coronavirus has infected more than 11 million people worldwide, killing more than 525,000. But despite the increasing toll, scientists still do not have a definitive answer to one of the most fundamental questions about the virus: How deadly is it?
A firm estimate could help governments predict how many deaths would ensue if the virus spread out of control. The figure, usually called the infection fatality rate, could tell health officials what to expect as the pandemic spreads to densely populated nations like Brazil, Nigeria and India.
In even poorer countries, where lethal threats like measles and malaria are constant and where hard budget choices are
    routine, the number could help officials decide whether to spend more on oxygen concentrators or ventilators, or on measles shots and mosquito nets.
The question became even more complex last month, when the Centers for Disease Control and Prevention released data suggesting that for every documented infection in the United States, there were 10 other cases on average that had gone unrecorded, probably because they were very mild or asymptomatic.
If there are many more asymptomatic infections than once thought, then the virus may be less deadly than it has appeared. But even that calculation is a difficult one.
On Thursday, after the World Health Organization held a two-day online meeting of 1,300 scientists from around the world, the agency's chief scientist, Dr Soumya Swaminathan, said the consensus for now was that the IFR is about 0.6% - which means that the risk of death is less than 1%.
Although she did not note this, 0.6% of the world's population is 47 million people, and 0.6% of the US population is 2 million people. The virus remains a major threat.
At present, countries have very different case fatality rates, or CFRs, which measure deaths among patients known to have had COVID-19. In most cases, that number is highest in countries that have had the virus the longest.
According to data gathered by The New York Times, China had reported 90,294 cases as of Friday and 4,634 deaths, which is a CFR of 5%. The United States was very close to that mark. It has had 2,811,447 cases and 129,403 deaths, about 4.6%.
Those percentages are far higher rates than the 2.5% death rate often ascribed to the 1918 flu pandemic. Still, it is difficult to measure fatality rates during pandemics, especially at the beginning.
In the chaos that ensues when a new virus hits a city hard, thousands of people may die and be buried without ever being tested, and certainly without them all being autopsied.
It is never entirely clear how many died of the virus and how many died of heart attacks, strokes or other ills. That has happened in both New York City and in Wuhan, China, where the outbreak began.
Normally, once the chaos has subsided, more testing is done and more mild cases are found - and because the denominator of the fraction rises, fatality rates fall. But the results are not always consistent or predictable.
Ten sizable countries, most of them in Western Europe, have tested bigger percentages of their populations than has the United States, according to Worldometer, which gathers statistics. They are Iceland, Denmark, Spain, Portugal, Belgium, Ireland, Italy, Britain, Israel and New Zealand.
But their case fatality rates vary wildly: Iceland's is less than 1%, New Zealand's and Israel's are below 2%. Belgium, by comparison, is at 16%, and Italy and Britain at 14%.
Both figures - the infection fatality rate and the case fatality rate - can differ quite a bit by country.
So far, in most countries, about 20% of all confirmed COVID-19 patients become ill enough to need supplemental oxygen or even more advanced hospital care, said Dr Janet Diaz, head of clinical care for the WHO's emergencies program.
Whether those patients survive depends on a host of factors, including age, underlying illnesses and the level of medical care available.
Death rates are expected to be lower in countries with younger populations and less obesity, which are often the poorest countries. Conversely, the figures should be higher in countries that lack oxygen tanks, ventilators and dialysis machines, and where many people live far from hospitals. Those are also often the poorest countries.

The WHO and various charities are scrambling to purchase oxygen equipment for poor and middle-income nations in which the coronavirus is spreading.
And now, new factors are being introduced into the equation. For example, new evidence that people with Type A blood are more likely to fall deathly ill could change risk calculations. Type A blood is relatively rare in West Africa and South Asia, and very rare among the Indigenous peoples of South America.
    -The New York Times

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