Characterizing Spatial Accessibility of COVID-19 Testing and Vaccination Sites using Dasymetric Mapping and GIS

Abstract. The COVID-19 pandemic accentuated existing health disparities in the U.S., inflicting staggeringly disproportionate rates of exposure, infection and death among racial and ethnic minority populations. Early evidence in 2020 had suggested that testing locations were not equitably accessible to racial/ethnic minority populations, and thus, increased the likelihood of unnoticed virus spread in minority communities. Additionally, racial/ethnic minority populations have been less likely to be vaccinated for COVID-19 as of February 2021, when vaccination had just started rolling out. In this study, we use Intelligent Dasymetric Mapping (IDM) and GIS Service Area analysis to examine spatial access to testing and vaccination sites in the Denver metropolitan area in January 2021, when testing and vaccination access was limited and competitive. Our results indicate that the racial/ethnic composition in total service areas with short walking- or driving-travel times was similar to the expected racial/ethnic composition of the Denver metro area, with minority populations slightly overrepresented in the total service areas. To ensure equitable vaccination and testing in minority communities in the future, in addition to ensuring spatial access, policymakers and health officials should increase community outreach, establish trust, and lower potential costs. Our study demonstrates the value of IDM in studying public health access.