Analysing and comparing the COVID-19 data: The closed cases of Hubei and South Korea, the dark March in Europe, the beginning of the outbreak in South America

Stefano De Leo; Gabriel Gulak Maia; Leonardo Solidoro

II. Spreading rate and the α factor II. Spreading rate and the α factor Fig. 1 shows the total number of confirmed cases per million residents in 10 European countries, the Chinese Province of Hubei and South Korea since day 0 (21 January) of the outbreak data. We can see that for nearly 30 days the spreading of COVID-19 is more or less confined to China, with a steep increase everyday. Around day 20 (10 February), the total number of confirmed cases in Hubei starts to stabilise to nearly 1200 TCCpM. A similar curve can be observed for South Korea. South Korea's population is of comparable size to Hubei's population, as can be seen in the table annexed to Fig. 1 , but their TCCpM curve stabilises much faster and at a much lower value, approximately 200 TCCpM. As of now, no other country studied in this work has reached a similar stabilisation. This striking difference might be due to the timely action of the South Korean authorities in adopting preventive measures to contain the outbreak, including, among others, the large number of tests performed. For example at day 48 (9 March), when both Italy, with its 9172 total confirmed cases and South Korea, with its 7478 ones, reached 150 TCCpM, see Fig. 2 , the number of tests performed in Italy (60761) was three and a half times smaller than the ones carried out in South Korea (210144). Fig. 2 gives a better idea of how the TCCpM spreading rate in the European countries changes from around day 50 up to around day 70. The time series show, for instance, that at day 48, Italy has the same TCCpM as South Korea. At day 52, Italy overtakes and Switzerland reaches South Korea. At day 64, Switzerland and Italy both overtake Hubei and, finally, after 4 days, Spain overtakes Hubei and Italy, and reaches Switzerland (overtaking it at day 72 as shown in Fig. 1 ). The complete time series can be found updated and in animated format in the website [8] .