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The figures for the coronavirus in Germany hide a riddle: the country has 19,000 confirmed cases and only 68 deaths. That leaves a fatality rate of 0.36%, much lower than in France (2%), Spain (4%) and Italy (8%). We know that this difference is influenced by Germany's ability to carry out thousands of tests. But there must be something else. Germany's case fatality rate is also exceptionally low compared to South Korea (1%), whose diagnostic capacity is also considered high. So how do we explain the German case? On Friday, the spokesman for the Spanish Health Ministry, Fernando Simon, said that they do not know. And neither do the German authorities have a definitive explanation. But there are at least three hypotheses.
1. It is possible that the virus broke out in Germany later. The first local outbreak of contagion within Europe was detected in Italy and was well advanced when it emerged: that is why the dead arrived quickly there. It was only a week from the infected number 20 to the dead number 20. This suggests that the outbreak had been active for weeks, because it takes two or three weeks for the disease to cause death.
The alarm in Italy made European countries redouble their detection efforts. In Spain, the number of detected cases of an outbreak that was actually already here multiplied.
The first cases were also detected in Germany, but their outbreak was probably at an early stage. "Germany recognized its outbreak very early. We are two or three weeks ahead of some neighbouring countries," virologist Christian Drosten told Zeit. "We did it because we made a lot of diagnoses, we tested a lot. We certainly missed cases in that first phase. But I don't think we missed a major outbreak.
That could explain their lower mortality rate. For two reasons. First, because if Germany has detected the cases early on, it will have detected more young people, who are the first to be infected (they travel more and have more contact with foreigners). Young people are more resistant to the virus. Deaths are more common when the virus advances and older people become infected.
The other reason is that deaths take time to occur. In many countries we have seen death rates rise over time. This is what happened in South Korea, where the tests are being exhaustive and mortality has doubled from 0.5% to 1.1% between 1 and 20 March. If the outbreak in Germany is more recent than in Spain or Italy, its fatality figures could increase.
2. The sick Germans are younger. In Germany, the age of a sample of those infected is published daily, so we know that the average is 47 years old and that only 20% are over 60. These figures are similar to those of Korea (I), but very different from those of Italy, where the average age of those infected - which are detected - is 66 years and where 58% are over 60 years old (I). The oldest Covid-19 patients are cases with a higher risk. The population pyramid of each country could also have an influence. Italy is the European country with the most over-65s (26%), while in Korea they are only 14%. But that doesn't help explain the German case, where 25% of the inhabitants are 65 or older.
Cultural factors may also play a role. Data from China says that between 75% and 80% of Covid-19 infections have occurred in families, as Bruce Aylward of the WHO explained to The New York Times. But daily contact between young and old is not the same in all societies. As Moritz Kuhn of the University of Bonn (Germany) suggests, people between 30 and 49 years old living with their parents exceed 20% in Italy, China or Japan, while in Germany they are just over 10%.
3. Behind everything are the tests. Germany has ensured through the Robert Koch Institute, the center responsible for disease control, that it can perform 160,000 tests per week. The country could have done up to 4,000 tests per million people, far from the 625 per million that Spain has done. It is clear that better detection reduces the gross death rates to bring them closer to reality: if you count all the infections - including the mildest ones - the death rate per infected person will be lower.
This is also what the numbers from South Korea suggest. It is the country that has done the most testing (more than 5,000 per million inhabitants), and although its outbreak is now several weeks old, it is still one of the countries with the lowest lethality, 1.1%, which is often used as a reference.
The low lethality of the virus in Germany is probably due to a mixture of several things. Its figures will probably remain far below those of Spain and Italy, as long as the country is still able to test massively. But if another factor is that your outbreak is at an earlier stage, your death numbers will increase and the lethality will rise. The question is how much.
