What variables can better predict the number of infections and deaths worldwide by SARS-CoV-2? Variation through time

Garcia de Alcaniz, J. G.; Romero-Lopez, J.; Martinez, R. P.; Lopez-Rodas, V.; Costas, E.

Lack of knowledge is the main problem we face in the global Covid-19 pandemic. SARS-CoV-2 is a new virus of which there were no previous studies. Using data from 50 very different countries and by means of a regression analysis, we studied the degree to which a series of variables (health indicators, environmental parameters, economic and social indicators, general characteristics of the country) were able to predict the number of people infected and killed by Covid-19. We also studied how these variables were changing their ability to predict the number of infected and dead by covid-19 during a 3 months period (March, April, May). The number of deaths by Covid-19 can always be predicted with great accuracy from the number of infected, regardless of the characteristics of the country (which has better or worse health, greater or lesser wealth, regardless of its population structure, etc.). Epidemiological measures to prevent transmission, mainly travel and mobility restrictions, proved to be much more efficient than having large hospital and medical resources. Inbound tourism turned out to be the variable that best predicts the number of infected (and, consequently, the number of deaths) happening in the different countries. Electricity consumption and degree of air pollution of a country (CO2 emissions, nitrous oxide and methane) are also capable of predicting, with great precision, the number of infections and deaths from Covid-19 in that country. Characteristics such as the area and population of a country also can predict, although to a lesser extent, the number of infected and dead. In contrast, a series of variables, which in principle would seem to have a greater influence on the evolution of Covid-19 (hospital bed density, Physicians per 1000 people, Researches in R & D, urban population, etc.), turned out to have very little ability to predict both the number of infected and the number of deaths from Covid-19. All this may explain why the countries that opted for social withdrawal policies since the start of the pandemic outbreak obtained better results.