“15% fatality rate” from coronavirus (2019-nCoV) infection was based only on initial cases; actual rate closer to 3%

CLAIM
"Coronavirus hits 15% fatality rate"

SOURCE: , , 25 Jan. 2020  

DETAILS
Misleading: The 15% fatality rate from coronavirus (2019-nCoV) infection reported in a Lancet study was based only on the first 41 cases detected. The current overall fatality rate, based on more than 800 confirmed cases, is closer to 2 - 3%.
KEY TAKE AWAY
The 15% fatality rate from coronavirus (2019-nCoV) applied only to the initial cluster of 41 patients with confirmed infection and severe symptoms, as reported in The Lancet. Coronavirus infections can also produce mild symptoms, which likely went undetected. The mortality rate based on a group of more than 800 patients with laboratory-confirmed infection suggests that the fatality rate is closer to 3%.

FULL CLAIM: "Coronavirus hits 15% fatality rate"

REVIEW


The article containing this claim was published on 25 January 2020. The headline claims that the novel coronavirus from Wuhan, China, provisionally named 2019-nCoV, causes a 15% fatality rate.

The article bases its claim on a study published January 2020 in The Lancet, which examined the clinical features and outcomes of 2019-nCoV infection in the first cluster of 41 cases[1]. Six people in this initial cohort died, bringing the fatality rate to approximately 15%.

However, these initial cases were only detected because the patients experienced severe symptoms. Infection with 2019-nCoV can also produce mild illness and symptoms of the common cold or flu. Patients with mild symptoms are less likely to seek medical attention and therefore less likely to be definitively diagnosed. Therefore, the 15% fatality rate is likely an overestimation.

Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center, explained this phenomenon in a recent New York Times article:

When we get a new infectious disease, we learn about the most severe cases first, the top of the pyramid as it were […] As the investigation goes on, we often learn there are less severely infected people, and even people who are infected who don’t get sick at all.

An estimate of overall mortality, rather than simply initial mortality, was published on 24 January 2020, and was based on data from more than 800 confirmed cases. In this cohort, 25 patients died, bringing the fatality rate closer to 3%[2]. A New York Times article published on 31 January 2020 also reports the same estimate.

A 24 January commentary in The Lancet explained that any estimates of fatality “should be treated with great caution because not all patients have concluded their illness (i.e., recovered or died) and the true number of infections and full disease spectrum are unknown.”

Because the outbreak is still underway, and many infections have yet to be discovered or have not concluded, the exact mortality from 2019-nCoV is unknown. However, it is very likely much lower than 15%.

While it is important to be vigilant during this outbreak, it is also necessary to put the dangers of the new coronavirus in perspective. For example, influenza has existed for much longer than 2019-nCoV and thus has had more global impact, yet the public in general remains unconcerned about the seasonal flu. This is in spite of a report by the U.S. Centers for Disease Control and Prevention (CDC) estimating that the seasonal flu “has resulted in between 9 million – 45 million illnesses, between 140,000 – 810,000 hospitalizations, and between 12,000 – 61,000 deaths annually since 2010.”

[Scientific research on 2019-nCoV is ongoing. This review will be updated as new information becomes available.]

REFERENCES

     

Published on: 03 Feb 2020 | Editor:

Health Feedback is a non-partisan, non-profit organization dedicated to science education. Our reviews are crowdsourced directly from a community of scientists with relevant expertise. We strive to explain whether and why information is or is not consistent with the science and to help readers know which news to trust.
Please get in touch if you have any comment or think there is an important claim or article that would need to be reviewed.

ifcn-fact-checkers-code-of-principles-signatory