September 19, 2020

Coronavirus: What are the chances of dying?

Two medical workers put on protective clothing at a hospital to treat coronavirus patients in Wuhan, China.

Researchers currently think that between five and 40 coronavirus cases in 1,000 will result in death, with a best guess of nine in 1,000 or about 1%.

On Sunday, Health Secretary Matt Hancock said the UK government’s “very best assessment” was that the mortality rate was “2% or, likely, lower”.

But it depends on a range of factors: your age, sex and general health and the health system you are in.

How hard is it to work out the death rate?

It is PhD-level hard. Even counting cases is tricky.

Most cases of most viruses will go uncounted because people tend not to visit the doctor with mild symptoms.

The different death rates we are seeing reported around the world are unlikely to be due to different versions of the virus.

According to research by Imperial College, it’s because different countries are better or worse at spotting the milder, harder to count cases.

Triangle graph of cases, from deaths to mild cases

So under-reporting cases makes it easy to overestimate the death rate. But you can also get it wrong in the other direction.

It takes time before an infection results in recovery or death.

If you include all cases that haven’t yet had a chance to run their course, you will underestimate the death rate because you are missing the cases that will end in death later.

Scientists combine individual pieces of evidence about each of these questions to build a picture of the death rate.

For example, they estimate the proportion of cases with mild symptoms from small, defined groups of people who are monitored very tightly, like people on repatriated flights.

But slightly different answers from those pieces of evidence will add up to big changes in the overall picture.

If you just use data from Hubei, where the death rate has been much higher than elsewhere in China, then the overall death rate will look much worse.

So scientists give a range as well as a best current estimate.

But even that doesn’t tell the full story because there is no single death rate.

What’s the risk for people like me?

Some types of people are more likely to die if they contract coronavirus: the elderly, the unwell and, maybe, men.

In the first big analysis of more than 44,000 cases from China, the death rate was ten times higher in the very elderly compared to the middle-aged.

Death rates for different groups
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The death rates were lowest for the under 30s – there were eight deaths in 4,500 cases.

And deaths were at least five times more common among people with diabetes, high blood pressure or heart or breathing problems.

There was even a slightly higher number of deaths among men compared to women.

All of these factors interact with each other and we don’t yet have a complete picture of the risk for every type of person in every location.

Someone wearing a face mask stands on the balcony of the quarantined Diamond Princess cruise ship

What’s the risk for people where I live?

A group of 80-year-old men in China could have very different risks to men of the same age in Europe or Africa.

Your prognosis also depends on the treatment you get.

In turn, that depends on what is available and the stage of the epidemic.

If the epidemic takes off, then healthcare systems could get swamped with cases – there are only so many intensive care units or ventilators available in any given area.

Royal Free Hospital in London

Is it more dangerous than flu?

We can’t compare mortality rates because many people with mild flu symptoms choose never to visit a doctor.

So we don’t know how many cases there are of flu, or any new virus every year.

But flu continues to kill people in the UK, as it does every winter.

As the data evolves, scientists will develop a clearer picture of who would be most at risk should a coronavirus outbreak arrive in the UK.

The basic advice from the WHO is that you can protect yourself from all respiratory viruses by washing your hands, avoiding people who are coughing and sneezing and trying not to touch your eyes, nose and mouth.

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