Infection fatality ratio and case fatality ratio of COVID-19

The infection fatality ratio (IFR) is the risk of death per infection and is one of the most important epidemiological parameters. Enormous effort s have been undertaken to estimate the IFR for COVID-19. This study examined the pros and cons of several approaches. It is found that the frequently used approaches using serological survey results as the denominator and the number of confirmed deaths as the numerator underestimated the true IFR. The most typical examples are South Africa and Peru (before official correction), where the confirmed deaths are one-third of the excess deaths. We argue that the RT-PCRbased case fatality ratio (CFR) is a reliable indicator of the lethality of COVID-19 in locations where testing is extensive. An accurate IFR is crucial for policymaking and public-risk perception. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

The infection fatality ratio (IFR) is a crucial epidemiological parameter for assessing the risk of death per infection, but estimating the IFR for COVID-19 requires avoiding methods that underestimate the true situation. Research suggests that in areas with extensive testing, RT-PCR-based case fatality ratio (CFR) can serve as a reliable indicator of the lethality of COVID-19.