Madrid has been the epicenter of COVID-19 in Spain, primarily due to its high population density and mobility. The city has 3.3 million people, with 6.8 million across the metropolitan area. Up to March 15 2021, roughly 605 000 persons had been diagnosed with SARS-CoV-2 infection and 14 000 had died in the Madrid region (Ministerio de Sanidad, 2021; Instituto Nacional de Estadística, 2021). These figures refer to laboratory-confirmed cases, which underestimate the true number as testing access was limited during the earlier stages of the pandemic (Soriano and Barreiro, 2020).
