As vaccine eligibility grew, so did gaps in who got protected.

As the U.S. rolled out COVID-19 vaccines, a troubling pattern emerged: the very communities that often need protection the most were getting left further behind. An analysis of county-level data from late 2020 through spring 2021 found that disparities in vaccination coverage by social vulnerability didn't shrink as eligibility expanded—they grew. By May 2021, adults living in counties with lower socioeconomic status, and in counties with higher percentages of households with children, single parents, and people with disabilities, had lower vaccination coverage. This paints a clear picture of where the vaccination effort encountered its toughest challenges. It's important to remember this is an observational look at patterns—it shows an association between county characteristics and lower coverage, but it can't pinpoint the exact causes or measure the precise size of the gaps. The data tells us where the holes in the safety net were, but not exactly why they formed.