Covid-19 outbreak made me look at some data available from European Centre for Disease Prevention and Control (ECDC). The calamity has a lot of emotionally loaded media coverage, I’ll focus on numbers and conclusions that can be made from them. I use data coming from documented sources considered reliable. The data show results produced by same virus in various countries are widely different.
WHO defines pandemic as worldwide spread of a new disease. According to table below Covid-19 indeed matches this definition, it was detected in almost every country. Please note worldwide population is around 7.8 billion, so cases detected as of 2020.03.22 08:00 represent 0.0039% of the world population. Pandemic evolution should be viewed using affected population size as reference.
| cases | deaths | count | |
|---|---|---|---|
| world | 305275 | 12942 | 179 |
| top | 282564 | 12636 | 20 |
| top 20 % share | 92.6 | 97.6 |
Countries with most cases detected are listed in table below, ECDC naming is preserved. The table represents ECDC data as of 03.22.
| GeoId | Cases | Deaths | Countries and territories | |
|---|---|---|---|---|
| 0 | CN | 81499 | 3267 | China |
| 1 | IT | 53578 | 4827 | Italy |
| 2 | US | 26747 | 340 | United_States_of_America |
| 3 | ES | 24926 | 1326 | Spain |
| 4 | DE | 21463 | 67 | Germany |
| 5 | IR | 20610 | 1556 | Iran |
| 6 | FR | 14459 | 562 | France |
| 7 | KR | 8897 | 104 | South_Korea |
| 8 | CH | 6077 | 56 | Switzerland |
| 9 | UK | 5018 | 233 | United_Kingdom |
| 10 | NL | 3631 | 136 | Netherlands |
| 11 | AT | 3024 | 8 | Austria |
| 12 | BE | 2815 | 67 | Belgium |
| 13 | NO | 1926 | 7 | Norway |
| 14 | SE | 1746 | 20 | Sweden |
| 15 | DK | 1326 | 13 | Denmark |
| 16 | PT | 1280 | 12 | Portugal |
| 17 | CA | 1231 | 13 | [Canada, CANADA] |
| 18 | MY | 1183 | 4 | Malaysia |
| 19 | BR | 1128 | 18 | Brazil |
How Covid-19 started – early stage
First Covid-19 cases were reported in China and China outbreak made the virus famous. The virus comes form group responsible for common cold, but this mutation causes in some fraction of cases acute respiratory problems, pneumonia and may result in patient death even if treated in proper hospital. There is no known working vaccine, nor medication targeting the virus, its elimination depends on patient immunological system. My understanding is Covid-19 causes cold like illness that for some cases results in life threatening complications. I am not a medical professional, it may be over simplified. My goal is estimate infection complications probability from available statistics.
Early stage definition
I define early stage of epidemic as period between 1st case and 300th cases detected in a country. The latter number is set arbitrary.
Early stage conclusions
- Early stage in China started end of Dec 2019
- Early stage in Europe started one month later than China
- Early stage lasted 3 to 5 weeks depending on country
- New year holiday season promoted silent transfer of virus
- Common cold symptoms allow Covid-19 move under disguise
- Covid-19 requires specialized tests to confirm
- Time from infection to life threatening symptoms development is probably long
- Steady buildup of acute respiratory problems cases in hospitals triggered epidemic alarm, increased testing followed
- Once road Covid-19 tests started, number of detected cases surged
Developed stage definition
I define epidemic is in developed stage in a country once cumulative number of detected cases exceeds 200. There is an overlap between early (up to 300) and developed stage (more than 200) and it is deliberate. Again 200 cumulative cases detected is arbitrary.
Developed stage so far (03.22 data)
China epidemic subsided. Unfortunately new cases are building up in Europe. Italy is most heavily hit. However close to 54 thousands detected cases in Italy translates to 0.09% of population (60 million). From pure volume perspective this is not a countrywide disaster yet, it may or may not develop into one.
Mortality rate
We define cumulative mortality rate dividing cumulative deaths by cumulative cases. Please note the latter number may be much less accurate than the former. We almost all fatalities with CoVID-19 symptoms are tested for virus, while general population is not. Thus actual number of cases can be much higher than detected one.
We see initial mortality rate was around 2-3%, which is consistent with WHO findings for China outbreak. Then the mortality rate started to climb. I believe it resulted from shortage of tests. Available ones were used on cases with severe symptoms qualifying for hospital treatment. Light cases were left undetected.
Mortality comparison
Following pictures show cumulative detected cases and mortality for top 8 countries selected after cumulative cases
- China moved from 2% to 4%
- Spain moved from 1% to 5%
- Italy and Iran moved form 2% to 8-9% range
- USA moved down from 3.5% to 1.3%
- France moved up from 1.5% to 4% range
- South Korea moved from .5% to 1.2% range
- Germany stays below 0.3% and it has 20 thousands cases detected, this is 1/3 of Italy volume
Germany case suggests actual Covid-19 mortality may be much lower than data from other countries suggest. Let’s compare mortality rates on a single chart. I’ve seen data suggesting Germany tested over 250 thousands people for Covid-19.
Mortality comparison for selected countries
We see a wide difference in mortality rate among detected cases. Italy is at 9% level, while Germany at 0.3% level. This represents a factor of 30 difference. I attribute this difference to the scale of testing. Germany tests cover much broader population, while Italy focuses testing on severe cases. In result true number of Covid-19 cases is under reported in Italy thus pushing mortality rate up. I’ll move further discussion of Covid-19 mortality to another post.