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This fact brief was originally published as an experiment to test the concepts behind fact briefs.

Readers should be aware that while there is still a lot of useful information in fact briefs like this one, not all of them reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date, don't hesitate to contact us at support@gigafact.org.

FACT BRIEF

Is the ‘case fatality rate’ a reliable measure of the deadliness of the coronavirus?

Thursday, December 10, 2020

By Esther Honig

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The oft-cited “case fatality rate” of the coronavirus has been widely misinterpreted. It is not accurate to assume that a reported fall in the rate means the disease has somehow become less life-threatening.

The rate is calculated by dividing deaths attributed to COVID-19, which is the disease caused by the coronavirus, by the number of cases of infection by the virus. With limited testing, the number of confirmed infections is unreliable. With the disease's unpredictable course, timing and estimates of fatalities are unreliable. The calculations may only be reliably accurate at the end of the pandemic, when everyone infected has either recovered, or died.

Excess mortality rate may be a better representation of COVID-19's impact. This figure compares the number of reported deaths by all causes to what would have been expected in a normal year.

This fact brief is responsive to conversations such as this one.

Sources

Our World in Data: What do we know about the risk of dying from COVID-19?

Our World in Data: Trends in mortality data for COVID-19

World Health Organization: Estimating mortality from COVID-19

Centers for Disease Control: Excess deaths associated with COVID-19

ABOUT THE CONTRIBUTOR

Gigafact

Between 2020 and 2022, under close editorial supervision, Gigafact contracted a group of freelance writers and editors to test the concepts for fact briefs and provide inputs to our software development process. We call this effort Gigafact Foundry. Over the course of these two years, Gigafact Foundry writers published over 1500 fact briefs in response to claims they found online. Their important work forms the basis of Gigafact formats and editorial guidelines, and is available to the public on Gigafact.org. Readers should be aware that while there is still a lot of relevant information to be found, not all fact briefs produced by Gigafact Foundry reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.

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About fact briefs published on Gigafact

Fact briefs are short, credibly sourced summaries that offer “yes/no” answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact —a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all fact briefs here.