Rapid characterization of the propagation of COVID-19 in different countries

BACKGROUNDCOVID-19 has spread rapidly, and there are still many characteristics of this new disease to be unveiled. We propose a simple method to calculate a "figure of merit" FC to provide an early characterization of the disease status in country C. METHODSWe use mathematical tools to adjust a Gaussian function to the daily increase of infected patients. Maximum value and full width half maximum of the Gaussian are characteristics of the development of the development of the pandemic in each country. These parameters are supplemented by the testing volume and the mortality rate to produce just one characterizing parameter: FC. In addition, the stability of the Gaussian fits was calculated within an entire week towards the end of the study period. Seventeen different countries were fully considered, while others are considered when discussing particular properties. Data employed is publically available. FINDINGSFitted Gaussian functions render effective information about the development of COVID-19. The number of critical days vary between 11 (South Korea) and 52 (Mexico). FC varies between 1 (Australia) and 899 (Mexico). The epidemic appears stabilized in some countries and unstable in others. Some large countries are experiencing fast development of the propagation of the disease with high FC. A correlation between low (high) values of the mortality rate (and to some extent FC) and the presence (absence) of BCG vaccination is exposed. INTERPRETATIONThe adjustment of a Gaussian to daily data of COVID-19 in each country reveals the different propagation dynamics, properly characterized by the parameters proposed here. Testing plays a clear role to control the spread of the disease. Mortality rate spans more than one order of magnitude and is somewhat related to permanent massive BCG vaccination. The figure of merit, FC, introduced here spans more than 2 orders of magnitude which makes it a useful indicator to quickly find out the status of the pandemics in each territory. Geography plays a role: low population density and isolated countries can be efficient in controlling the spread of the disease. HIGHLIGHTSO_LIAn easy-to-evaluate parameter is defined to rapidly establish the status of the evolution of COVID-19 in any given territory. 17 countries in 4 continents are chosen to apply it and compare different evolutions. C_LIO_LIThe parameter or figure of merit (FC) is dynamic: it combines testing, mortality rate, and characteristics of the Gaussian function that fits the new daily contagions. C_LIO_LIFC spans more than two orders of magnitude which makes it a very sensitive indicator to promptly detect second waves or local outbreaks. C_LIO_LIIt is found that countries with massive BCG vaccination present low COVID-19 mortality rates and low values for FC. C_LI