06 April 2020 | News | By Ankit Kankar | Special Reporting COVID19 - The Global Pandemic
There is no single figure of CFR for any particular disease. The CFR varies by location, and is typically changing over time.
Image Source : Public Domain
CFRs vary widely between countries, from 0.2% in Germany to 7.7% in Italy. But it says that this is not necessarily an accurate comparison of the true likelihood that someone with COVID-19 will die of it.
We do not know how many cases are asymptomatic versus symptomatic, or whether the same criteria for testing are being applied between countries. Without better and more standardised criteria for testing and for the recording of deaths, the real mortality rate is unknown. As the paper says, to understand the differences in CFR and how they should guide decision-making, we need better data.
But if we’re careful to acknowledge its limitations, CFR can help us to better understand the severity of the disease and what we should do about it.
This chart shows how these early CFR values compare. You can see the total number of confirmed cases of COVID-19 (on the x-axis, going across) versus the total number of deaths (on the y-axis, going up).
The grey lines show a range of CFR values – from 0.25% to 10%.
Where each country lies indicates its CFR – for instance, if a country lies along the 2% line, its current confirmed cases and death figures indicate it has a CFR of 2%.
The second chart shows how the CFR has changed over time in countries that have had over 100 confirmed cases.
We have excluded countries which still have a relatively small number of confirmed cases, because CFR is a particularly poor metric to understand mortality risk with a small sample size.
We see this if we look at the trajectory of cases and deaths in Iran: on February 24th it had 2 confirmed cases and 2 deaths, an implausible CFR of 100%. With time its CFR begins to fall, as the number of confirmed cases increases. By the time it has seen hundreds of cases, the CFR drops to around the level seen in other countries.
Source : Our World In Data