Rural US counties with low COVID-19 vaccination rates had 2.4 times more infections per 100,000 people than urban counties amid the summer 2021 Delta surge, according to a study published yesterday in JAMA Network Open.A team led by University of Cincinnati researchers conducted an ecological data visualization analysis using Johns Hopkins University and Centers for Disease Control and Prevention (CDC) data to investigate the link between rates of COVID-19 vaccination and Delta COVID-19 infections from Jul 1 to Aug 31.
Colorado, Georgia, Texas, Virginia, and West Virginia were excluded from the study because their vaccination data were incomplete or unreliable.Surge started in cities but thrived in rural areasCounties with COVID-19 vaccination rates lower than 30% saw infections increase from 190 per 100,000 residents during Jul 1 to 15 to 1,272 infections per 100,000 from Aug 16 to 31.
In comparison, during the same periods, COVID-19 infections in counties with vaccination rates higher than 50% rose from 71 per 100,000 residents to 531 per 100,000.Counties with vaccination rates lower than 30% had 2.4 more times new infections per 100,000 than those with 50% or higher vaccine coverage from Aug 16 to 31.
Rural counties made up 369 of 449 areas (82.2%) with low vaccine uptake and only 131 of 376 areas (34.8%) with high vaccination rates.Scatterplots illustrate that while the Delta surge first emerged in areas with high vaccine coverage, COVID-19 incidence was lower in those areas than in those with low vaccine uptake.