ORCID ID
Graduation Date
Spring 5-10-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Programs
Epidemiology
First Advisor
Patrick Maloney
Second Advisor
David Brett-Major
Abstract
Barriers to equitable access and uptake of Coronavirus 2019 (COVID-19) vaccines remain of critical importance to public health. This dissertation evaluated geographical disparities in vaccine access in Chapter Two, assessed individual- and community-level determinants of vaccine uptake in Chapter Three, and examined persistent vaccine refusal in Chapter Four.
In Chapter Two, a cross-sectional ecological study was conducted to evaluate geospatial accessibility to provider sites at four timepoints. An accessibility score was created using the Two Step Floating Catchment Area method and a spatial autoregressive model was used to identify indicators of vaccine access. Census tract level determinants for low vaccine accessibility included rurality, no internet access, overcrowded housing, and low educational attainment. Vulnerable populations, including low socioeconomic status (SES), minority, and elderly populations, exhibited a mostly positive association with accessibility.
In Chapter Three, a retrospective cohort study evaluating vaccine uptake of primary, monovalent booster, and bivalent booster series doses was performed using multilevel analysis. At the individual level, lower vaccination uptake was consistently observed among minorities and those with prior COVID-19 infection. Community-level factors associated with low uptake include county-level Republican partisanship and the Social Vulnerability Index (SVI) theme related to low SES. Older age and female sex positively predicted vaccine uptake, as did the county-level SVI theme related to the household characteristics.
In Chapter Four, a cohort of unvaccinated individuals with prior COVID-19 infection were asked for their reason for non-vaccination during case investigation. A modified Poisson regression was used to estimate the risk of unvaccinated status at follow-up against predictors. Ideology-based reasons for non-vaccination (including religious exemption and philosophical objection), older age, non-adherence to mitigation measures, and rural populations were at greater risk of persistent non-vaccination; minority status and hospitalization were correlated with vaccination.
Our study documented the urgency for equitable, accessibility focused vaccination efforts towards specific disadvantaged communities. Special consideration on community-level and individual-level barriers is necessary to curate context specific strategies to improve vaccine uptake. Vaccination patterns within unvaccinated and under vaccinated populations require further research and distinguishing sources of misinformation among ideologically similar communities could instigate reconsideration for vaccination.
Recommended Citation
Bai, Julia, "Navigating the Divide: COVID-19 Vaccine Access, Uptake, and Persistent Vaccine Refusal in Nebraska" (2025). Theses & Dissertations. 923.
https://digitalcommons.unmc.edu/etd/923
Permission for print
Comments
2025 Copyright, the authors