Association of Social Vulnerability, COVID-19 vaccine site density, and vaccination rates in the United States

The COVID-19 pandemic has disproportionately impacted Americans in socially vulnerable areas. Unfortunately, these groups are also experiencing lower vaccination rates. To understand how strategic vaccine site placement may benefit high vulnerability populations, we extracted vaccine site locations for 26 U.S. states and linked these data to county-level adult vaccination rates and the CDC 2018 Social Vulnerability Index rankings. We fit quasi-Poisson regression models to compare vaccine site density between the highest and lowest SVI domain quartiles, and assessed whether greater vaccine site density mediated or modified the relationship between social vulnerability and vaccination rates. We found that high vulnerability counties by socioeconomic status had more vaccine sites per 10,000 residents, yet this higher vaccine site density did not reduce socioeconomic disparities in vaccination rates. Persistent vaccination inequities may reflect other structural barriers to access. Our results suggest that targeted vaccine site placement in high vulnerability counties may be necessary but insufficient for the goal of widespread, equitable vaccination.