This is a strange case of difference in [fatality rate][1] between Chinese and Italian covid-19 outbreak.

In my knowdledge, fatality rate is a ratio between *deaths* from a certain disease compared to the *total number* of subjects diagnosed with the disease.

Starting from this assumption, I attempted to analyze difference in fatality rate between Chinese/Italian outbreak. Herein, I propose a reproducible R example for exploring this variable:

    # Import dataset from authoritative source: 
    # https://ourworldindata.org/coronavirus-source-data
    covid <- read.csv("http://cowid.netlify.com/data/full_data.csv")
    
    # Subsetting only data from China and Italy
    dataset <- subset(covid, location == "China" | location == "Italy")
    
    # Fatality ratio: is the proportion of deaths from a certain disease compared to the 
    # total number of people diagnosed with the disease for a certain period of time.
    dataset$fatality <- round(dataset$total_deaths/dataset$total_cases*100, 2)
    
    # Generating plot
    library(ggplot2)
    ggplot(dataset, aes(as.numeric(date), fatality, color = location, group = location))+
      geom_smooth(size= .5, alpha=.25, color = "gray65")+
      geom_line()+
      geom_point()+
      labs(x="Outbreak duration (days)", y= "Fatality rate (%)", color = "Location")+
      theme_light(14)

**EDT:**
[![enter image description here][2]][2]
**Bar Plot**

    # Generating bar plot
    library(ggplot2)
    ggplot()+
      geom_bar(data=subset(dataset, location == "China"), 
               aes(as.numeric(date), fatality, fill = "China"), 
               stat = "identity", position = position_dodge(), alpha = .75)+
      
      geom_bar(data=subset(dataset, location == "Italy"), 
               aes(as.numeric(date), fatality, fill = "Italy"), 
               stat = "identity", position = position_dodge(), alpha = .75)+
      
      labs(x="Outbreak duration (days)", y= "Fatality rate (%)", fill = "Location")+
      scale_fill_brewer(palette = "Set1")+
      theme_light(14)
[![enter image description here][3]][3]
From this basis, I'm a little bit confused about such difference in terms of fatality rate between the two analyzed countries. In fact, China has the maximum fatality rate at 4%, while Italy at more than 6%. For this reason I've two questions:

1) Is my computation correct?

2) If yes, why such a huge difference in terms of fatality rate? 


----------


**EDT II**

I would like to enanche this question reporting a recent *[Science][4]* paper which can partially explain these differences. In fact, *Li et al* reported that for each COVID+ patient, other 5-10 are undocumented COVID+ leading to missleading fatality rate. Moreover, as reported in the comments, to date, there are no univocal diagnostic methods wordwide.  


  [1]: https://en.wikipedia.org/wiki/Case_fatality_rate
  [2]: https://i.sstatic.net/02hyL.png
  [3]: https://i.sstatic.net/GToss.png
  [4]: https://doi.org/10.1126/science.abb3221