Coronavirus: What are the chances of dying and who is most at risk?

The illness caused by the new coronavirus, COVID-19, continues to spread across borders, but the risk of contracting it isn’t the same for everyone.

It depends on a range of factors — age, travel history, access to and quality of health care — but scientists are still working to determine exactly how deadly it is.

Here’s a look at what we know so far.

What are the chances of dying?

It’s hard to say at this point.

In Wuhan, China — where the virus first exploded — about two to four per cent of patients have died, according to the World Health Organization (WHO). Throughout the rest of China, the death rate is much lower, at around 0.7 per cent.

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Dr. Bruce Aylward, the Canadian doctor who led a WHO team to China to look into the epidemic, said the reason for the discrepancy between Wuhan and the rest of China is partly because of how early and fast the disease hit the city. In the beginning, “people didn’t know what we were dealing with,” he said, adding doctors were just learning how to treat it.

Now, with more accurate testing, milder cases are being diagnosed and isolated.

There are different factors to consider when identifying fatality rates, said Dr. Isaac Bogoch, an infectious disease specialist based out of Toronto General Hospital. He said it comes down to three things: each country knowing exactly how many people have the infection, good structures to report and confirm illnesses, and, simply, time.

“You can’t just take this as a snapshot in time just yet,”  he said. “There could be people who are critically ill, but they’re counted as alive when, in fact, they’re very likely to succumb to the illness in the coming week or weeks ahead.”

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He pointed to South Korea as an example of where improved testing has so far provided a clearer picture of fatalities.

“If you look at South Korea, they have thousands of cases there, but their rate is roughly 0.5 per cent. What they’ve done is offer very, very broad screening tests, picking up a large number of people who have very mild symptoms,” he said.

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“To really understand a case fatality rate, you have to know how many people have the infection. That is the denominator. We don’t know what the denominator is in many places, including South Korea, but I think South Korea has done a much better job in finding out what the denominator is by widening their screening.”

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Determining an overall death rate is challenging, according to researchers at Imperial College London in the U.K., because of the differences in how countries spot milder cases. The discrepancies in tracking cases make underreporting easy, which can skew a death rate.

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While deaths are reported and tallied quickly, the researchers say there is less information on those who have recovered.

But more mild cases being identified doesn’t make any mortality rate insignificant, Aylward told reporters at a routine WHO press conference earlier this month.

“The same number of people that were dying still die,” he said.

Who is the most at risk?

Until recently, most people diagnosed with COVID-19 outside of China had recently travelled there. Now there are significant clusters of the virus in Iran, Italy, South Korea and Japan.

The death toll is also climbing outside China. As of March 2, Japan had reported six deaths, Italy 34 and Iran 54. The United States had two.

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It’s older people — especially those with a history of chronic illness — who are the most at risk, experts believe.

A recent study by the Chinese Center for Disease Control and Prevention found that the virus has so far most seriously affected older people with pre-existing health problems.

The data suggests a person’s chances of dying from COVID-19 only increases with age, with the risk of dying particularly high among patients in their 70s and 80s.

So far, most of those who have died from the virus had “underlying health conditions,” such as hypertension, diabetes or cardiovascular diseases, the WHO said, which weakened their immune systems. The study shows about a 10 per cent mortality rate for coronavirus patients with heart disease and about seven per cent for those with diabetes.

Deaths are far rarer among younger people, the WHO says, but that doesn’t mean it’s impossible. While the severely ill are at the highest risk of death, a fraction of the mild cases prove fatal for unknown reasons, according to Aylward.

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A key example is the 34-year-old Chinese doctor who made headlines when he died from the virus mere weeks after sounding the alarm about the imminent outbreak.

However, the Chinese study found that, overall, about 80 per cent of coronavirus cases are mild.

Doctors and medical staff are inevitably more at risk of infection than those outside the industry, experts say. In the region of Lombardy, the epicentre of Italy’s outbreak, the government has formally requested permission to recall retired doctors and nurses, as well as expedite nursing students’ graduations, to help overwhelmed hospital emergency rooms.

Lombardy accounts for more than 984 of Italy’s 1,694 cases — with 10 per cent of those being doctors and nurses, now out of commission and in quarantine.

Is it more dangerous than the flu?

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The common cold and COVID-19 are both infectious respiratory illnesses. Both illnesses have similar symptoms but are caused by different viruses.

Canada saw more than 39,000 cases of influenza between 2018 and 2019. On average, it causes about 3,500 deaths each year.

COVID-19 has infected more than 89,000 people globally and caused over 3,000 deaths. Canada has 27 cases as of March 2, with no deaths.

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Seasonal flu kills more people because it infects far more people, but Bogoch says COVID-19 is likely to have a higher case fatality rate.

“But we won’t know by how much until we have more information and time.”

— With files from The Associated Press