How lethal is the novel coronavirus, and how many undetected cases there are? The importance of being tested.

Ugo Bastolla

ained by the time course of the epidemics and the number of tests, without the Fig.2 also reports data for China, Germany and Australia. In the case of China, I could only find the number of tests performed in the Guangdong province and estimated that the number of tests performed in the whole country was 3 times larger. If this estimate is approximately correct, the data suggests that the mortality rate of China is smaller than for other countries, which could be attributed to two factors: (1) The Chinese population is significantly younger (for instance, only 12% of the Chinese population has more than 65 years, compared to 23% for Italy). (2) China is closer to the extinction of the epidemics, where the extrapolation at infinite time becomes quite accurate, while at smaller time the extrapolation probably (and hopefully) overestimates the mortality rate. For Germany, I could only find the number of tests performed in private laboratories and estimated the total number of tests as the double of this number.