Clarifying the True Fatality Rate of Covid-19: Same as the Flu?

[updated Oct] Comparing fatality rate jargons may lead to nowhere, but there are better metrics to grasp the health toll of Covid-19.

Shin Jie Yong, MSc (Res)
Microbial Instincts
7 min readSep 8, 2020

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Image by United Nations COVID-19 Response at unsplash.com

Author’s note: Please see an update at the end of the article too.

On 11 March 2020, the National Institute of Allergy and Infectious Diseases (NIAID) told the U.S. Congress House Oversight and Reform Committee that the novel coronavirus — that causes Covid-19 — has a mortality rate of 10-times higher than the seasonal flu.

Specifically, at the congressional hearing, the NIAID director Dr. Anthony Fauci said, “The flu has a mortality rate of 0.1 percent. This [Covid-19 or SARS-CoV-2] has a mortality rate of 10 times that. That’s the reason I want to emphasize we have to stay ahead of the game in preventing this.”

10 x 0.1% = 1%.

In other words, Dr. Fauci reported that Covid-19 has a mortality rate of 1%, which he said had fallen from 2–3% after taking into account asymptomatic (i.e., symptomless) infections.

But what did Dr. Fauci mean by mortality rate?

In an editorial published on 29 February in the New England Journal of Medicine (NEJM)co-authored by Dr. Robert R. Redfield, director of the CDC, and Dr. H. Clifford Lane, deputy director of NIAID — Dr. Fauci stated that influenza “has a case fatality rate of approximately 0.1%.”

Therefore, Dr. Fauci refers to the case fatality rate (CFR) when he said, “The flu has a mortality rate of 0.1 percent.”

But he should have said the infection fatality rate (IFR). Why?

The CFR is the total number of deaths divided by the total number of people that have the disease’s symptoms. In contrast, the IFR is the total number of deaths divided by the total number of people that carry the infection.

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Shin Jie Yong, MSc (Res)
Microbial Instincts

Named Standford's world top 1% scientists | Independent science writer and researcher | Medium boost program's nominator | Powerlifter with national records