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Science

New coronavirus death rate estimates show how sharply the risk rises with age

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A patient with COVID-19 is treated at a hospital in Wuhan, China.
(AFP / Getty Images)

The fatality rate for people infected with the novel coronavirus is estimated to be less than 1%, according to a new study.

Among the those whose infections cause them to become sickened by the disease known as COVID-19, the fatality rate is 1.38%, the study authors estimate.

Both fatality rates vary greatly with age, according to the report in the medical journal Lancet.

For instance, the fatality rate for infected people in their 20s is 0.03%, compared with 4.3% for people in their 70s. Likewise, the fatality rate for twentysomethings with COVID-19 is 0.06%, versus 8.6% for those in their 70s.

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The oldest age group in the study is people who are 80 and up. For them, the fatality rate among people infected with the new coronavirus is 7.8%, rising to 13.4% among those sickened with COVID-19.

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The figures are based on an analysis of 70,117 people whose cases were confirmed with a laboratory test or a doctor’s exam between Jan. 1 and Feb. 11. They were reported Monday by a team led by infectious disease experts from Imperial College London.

Nearly three-quarters of the patients were in Wuhan, China, where the virus first emerged. The researchers noted that Wuhan’s health system “was quickly overwhelmed” and that the limited availability of medical services may have led to more deaths than would be experienced elsewhere.

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However, they added, the fatality estimates for non-Chinese patients turned out to be similar, suggesting “relatively little difference in health outcome.”

To arrive at their estimates, the study authors did more than simply divide the number of reported deaths by the number of people known to be infected with — and sickened by — the coronavirus.

To improve their accuracy, they examined health records to determine the average amount of time it takes for a patient to progress from his or her first symptoms to either recovery (just under 25 days, on average) or death (just under 18 days, on average).

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They adjusted their estimate of infections to account for the proportion of younger and older people in the population. They ran their models with the assumption that the virus was equally likely to “attack” people of all ages, and again assuming that it wasn’t.

If you’ve been infected with the coronavirus, the chances that you will become critically ill depend on many factors.

To estimate the fatality rate among people infected with the virus, the researchers focused on international residents of Wuhan who returned to their home countries when the severity of the outbreak became clear. That estimate was validated by additional calculations based on the fates of 3,711 passengers aboard the Diamond Princess cruise ship. (Among them, 712 had confirmed coronavirus infections and, as of March 25, 10 had died.)

The study authors came up with an overall infection fatality rate of 0.66%. Health officials around the world can use that figure to help make “decisions around appropriate mitigation policies to be adopted,” they wrote.

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The 1.38% fatality rate among people who develop COVID-19 could change as the pandemic evolves, the study authors wrote, but it is “our best estimate at the current time.”

They noted that it’s lower than the fatality rates for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), both of which are also caused by coronaviruses.

However, they wrote, “it is substantially higher than estimates from the 2009 H1N1 influenza pandemic.”


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