The density paradox: Are densely-populated regions more vulnerable to Covid-19?

The "density paradox" refers to the observation that some highly populated cities and countries have recorded a smaller number of Covid-19 cases than regions that are sparsely populated. We present empirical evidence on the role played by population density in spreading the coronavirus, based on cross-sectional data covering 172 countries (obtained from several sources, including the European Centre for Disease Prevention and Control, the World Bank and the Center for Health Security). The results, obtained by using the techniques of extreme bounds analysis (EBA) and variable addition tests, show that population density has a significantly positive effect on the number of cases but not the number of deaths, as the latter is better explained by measures of preparedness. Plausible explanations are presented for the results to conclude that the "density paradox" is not really a paradox. This paper makes a contribution by shedding more light on a frequently debated issue by using a completely different, and more robust, statistical techniques and by providing results that may be helpful for health and urban planners.