The Evolving Association of Social Determinants of Health and Vaccination Coverage Among Older Adults: A Neighborhood-Level Analysis of COVID-19.

Background

Older adults (aged 65 and older) faced a disproportionate burden of mortality during the COVID-19 pandemic, yet substantial geographical and sociodemographic disparities in vaccine uptake persisted within this vulnerable population.

Objective

To examine the temporal dynamics of COVID-19 vaccination rates among older adults and investigate the association between vaccination uptake and neighborhood-level social determinants of health (SDOHs), including disability and poverty.

Methods

COVID-19 vaccination data for older adult residents in Jefferson County, Kentucky, were obtained from the Kentucky Immunization Registry (KYIR). ZIP-code-level vaccination rates were calculated at three time points: 28 February 2021 (Q1), 31 May 2021 (Q2), and 31 May 2022 (Q6). The rates were linked to 2021 American Community Survey (ACS) ZIP code-level estimates of disability, poverty, and household composition. Two-dose COVID-19 vaccination rates stratified by race, ethnicity, and geographic region were used as outcome measures. Pearson correlation coefficients, bivariate, and multivariate linear models were used to estimate the association between COVID-19 vaccination rates and the SDOHs at the ZIP code level.

Results

Among the estimated 139,222 older adults, overall two-dose vaccination rates rose from 22.4% in Q1 to 77.5% by Q6. Significant regional disparities were observed early in the campaign, with Q1 rates ranging from 12.6% in the Southwest to 35.4% in the Inner East county regions. Bivariate analyses showed ZIP-code-level disability and poverty rates were negatively associated with ZIP-code-level vaccination uptake in Q1 (disability slope: -0.38; 95% CI, -0.63 to -0.13; poverty slope: -0.36; 95% CI, -0.65 to -0.07). By Q6, the negative association between disability and vaccination had weakened significantly and was no longer statistically significant, while the negative association between poverty rate and vaccination rate remained persistent across all time points.

Conclusions

The disability-associated gaps in older adults' vaccination rates were dynamic and narrowed over time, whereas the poverty-associated gaps remained persistent and static. The low uptake observed among Black and Hispanic older adults in historically underserved areas suggests that understanding the specific factors that most negatively associate with vaccination rates in these populations, such as specific disabilities, may mitigate structural barriers. Future public health interventions should prioritize socioeconomically disadvantaged neighborhoods and account for the evolving association of functional impairments and healthcare access.